Ilt3 Binding Molecules And Uses Therefor

ABSTRACT

The present invention provides binding molecules that specifically bind to ILT3, e.g., human ILT3 (hILT3), on antigen presenting cells, such as for example, monocytes, macrophages and dendritic cells (DC), e.g., monocyte-derived dendritic cells (MDDC). The binding molecules of the invention are characterized by binding to hILT3 with high affinity and downmodulating immune responses in vitro, e.g., downmodulating alloimmune responses; the production of inflammatory cytokines by dendritic cells, e.g., monocyte-derived dendritic cells (MDDC); the upregulation of costimulatory molecules by DC, e.g., MDDC; and/or calcium flux in monocytes. In addition, the binding molecules upregulate the expression of inhibitory receptors on dendritic cells, e.g., immature dendritic cells. Surprisingly, these same binding molecules which downmodulate immune responses in vitro, are immunostimulatory in vivo. 
     Various aspects of the invention relate to binding molecules, and pharmaceutical compositions thereof. Methods of using the binding molecules of the invention to detect human ILT3 or to modulate human ILT3 activity, either in vitro or in vivo, are also encompassed by the invention.

RELATED APPLICATIONS

This application is a continuation-in-part application of U.S. patentapplication Ser. No. 11/471,397, filed on Jun. 19, 2006, titled “ILT3BINDING MOLECULES AND USES THEREFOR”. This application claims thebenefit of priority to U.S. Provisional Application, U.S. Ser. No.60/814,931, filed on Jun. 19, 2006, titled “ILT3 BINDING MOLECULES ANDUSES THEREFOR”. The entire contents of each of these references arehereby incorporated by reference.

BACKGROUND OF THE INVENTION

Immunoglobulin-like transcript (ILT) 3 is a cell surface molecule thatis a member of the immunoglobulin superfamily. ILT3 is selectivelyexpressed by myeloid antigen presenting cells (APCs) such as monocytes,macrophages, and dendritic cells (DC). The cytoplasmic region of ILT3contains putative immunoreceptor tyrosine-based inhibitory motifs(ITIMs). Co-ligation of ILT3 to stimulatory receptors expressed by APCsresults in a blunting of the increased [Ca2+] flux and tyrosinephosphorylation triggered by these receptors. Signal extinction involvesSH2-containing protein tyrosine phosphatase 1, which is recruited byILT3 upon cross-linking. ILT3 can also function in antigen capture andpresentation. It is efficiently internalized upon cross-linking anddelivers its ligand to an intracellular compartment where it isprocessed and presented to T cells (Cella, et al. (1997) J. Exp. Med.185:1743-1751).

Thus, ILT3 is an inhibitory receptor that can negatively regulateactivation of APCs and can be used by APCs for antigen uptake. Thedevelopment of agents useful in modulating signaling via ILT3 would beof great benefit in modulating immune responses.

SUMMARY OF THE INVENTION

The present invention provides binding molecules that specifically bindto ILT3, e.g., human ILT3 (hILT3), on cells, such as antigen presentingcells, e.g., monocytes, macrophages and dendritic cells, e.g.,monocyte-derived dendritic cells. The binding molecules of the inventionare characterized by binding to hILT3 with high affinity anddownmodulating immune cell activation in vitro, e.g., downmodulatingalloimmune responses; the production of inflammatory cytokines bydendritic cells, e.g., monocyte-derived dendritic cells (MDDC); theupregulation of costimulatory molecules by DC, e.g., MDDC; and/orcalcium flux in monocytes. In addition, the binding molecules upregulatethe expression of inhibitory receptors on dendritic cells, e.g.,immature dendritic cells. Surprisingly, these same binding moleculeswhich downmodulate immune cell activation in vitro, areimmunostimulatory in vivo, e.g., upmodulate immune rsponses.

Accordingly, one aspect of the invention features a binding moleculecomprising the amino acid sequence of SEQ ID NO:1.

In another aspect, the invention features a binding molecule comprisingthe amino acid sequence of SEQ ID NO:2.

Yet another aspect of the invention features a binding moleculecomprising at least one complementarity determining region (CDR) aminoacid sequence selected from the group consisting of: SEQ ID NO:3, SEQ IDNO:4, and SEQ ID NO:5. In one embodiment, the binding molecule comprisesat least two complementarity determining region (CDR) amino acidsequences selected from the group consisting of: SEQ ID NO:3, SEQ IDNO:4, and SEQ ID NO:5. In another embodiment, the binding moleculecomprises at least three complementarity determining region (CDR) aminoacid sequences selected from the group consisting of: SEQ ID NO:3, SEQID NO:4, and SEQ ID NO:5.

Another aspect of the invention features a binding molecule comprisingat least one complementarity determining region (CDR) amino acidsequence selected from the group consisting of: SEQ ID NO:6, SEQ IDNO:7, and SEQ ID NO:8. In one embodiment, the binding molecule comprisesat least two complementarity determining region (CDR) amino acidsequences selected from the group consisting of: SEQ ID NO:6, SEQ IDNO:7, and SEQ ID NO:8. In another embodiment, the binding moleculecomprises at least three complementarity determining region (CDR) aminoacid sequences selected from the group consisting of: SEQ ID NO:6, SEQID NO:7, and SEQ ID NO:8.

Another aspect of the invention features a binding molecule comprisingthe CDRs shown in SEQ ID NOs: 3-8.

One aspect of the invention features a binding molecule comprising aheavy chain variable region comprising the amino acid sequence of SEQ IDNO:1 and further comprising a light chain variable region comprising theamino acid sequence of SEQ ID NO:2.

Another aspect of the invention features a binding molecule that bindsto ILT3 on human monocyte-derived dendritic cells (MDDC) and has abinding constant (Kd) of 0.9×10⁻⁹ or less.

In one embodiment, the binding molecule downmodulates immune cellactivation in vitro.

In another embodiment, the binding molecule upmodulates immune responsein vivo.

In yet another embodiment, the constant region of the binding moleculecomprises an IgG1 heavy chain constant region.

In one embodiment, the binding molecule binds to human ILT3 on dendriticcells

In another embodiment, the binding molecule binds to human ILT3 onmonocytes.

In yet another embodiment, the binding molecule downmodulates theproduction of inflammatory cytokines by dendritic cells in vitro.

In one embodiment, the binding molecule downmodulates the upregulationof costimulatory molecules on dendritic cells in vitro.

In another embodiment, the binding molecule upmodulates the expressionof inhibitory receptors on dendritic cells in vitro.

In one embodiment, the binding molecule is a mouse antibody.

In another embodiment, the binding molecule is a monoclonal antibody orantigen binding fragment thereof.

In yet another embodiment, the binding molecule is a humanized orchimeric antibody.

Another aspect of the invention features a composition comprising abinding molecule of the invention and a pharmaceutically acceptablecarrier.

In one embodiment, the composition further comprises at least oneadditional therapeutic agent which upmodulates an immune response in asubject.

One aspect of the invention features a method for upmodulating an immuneresponse in a subject, comprising contacting a cell from the subjectwith an anti-ILT3 antibody that inhibits immune cell activation invitro.

Another aspect of the invention features a method for downmodulatingtransplant rejection in a subject, comprising contacting a cell from thesubject with a binding molecule of the invention, and re-introducing thecell into the subject at the time of or prior to transplantation suchthat transplant rejection in a subject is downmodulated.

Yet another aspect of the invention features a method for treatingcancer in a subject, comprising contacting a cell with a bindingmolecule of the invention, such that cancer is treated in a subject.

In one embodiment, the type of cancer is selected from the groupconsisting of: pancreatic cancer, melanomas, breast cancer, lung cancer,bronchus cancer, colorectal cancer, prostate cancer, pancreas cancer,stomach cancer, ovarian cancer, urinary bladder cancer, brain or centralnervous system cancer, peripheral nervous system cancer, esophagealcancer, cervical cancer, uterine or endometrial cancer, cancer of theoral cavity or pharynx, liver cancer, kidney cancer, testicular cancer,biliary tract cancer, small bowel or appendix cancer, salivary glandcancer, thyroid gland cancer, adrenal gland cancer, osteosarcoma,chondrosarcoma, and cancer of hematological tissues.

One aspect of the invention features an isolated nucleic acid moleculecomprising a nucleotide sequence encoding a heavy chain variable regioncomprising the nucleotide sequence of SEQ ID NO:9.

Another aspect of the invention features an isolated nucleic acidmolecule comprising a nucleotide sequence encoding a light chainvariable region comprising the nucleotide sequence of SEQ ID NO:10.

Yet another aspect of the invention features an isolated nucleic acidmolecule comprising a nucleotide sequence encoding at least one CDRselected from the group consisting of: SEQ ID NO:11, SEQ ID NO:12, andSEQ ID NO:13. In one embodiment, the isolated nucleic acid moleculecomprises at least two CDRs. In another embodiment, the isolated nucleicacid molecule comprises three CDRs.

Another aspect of the invention features an isolated nucleic acidmolecule comprising a nucleotide sequence encoding at least one CDRselected from the group consisting of: SEQ ID NO:14 SEQ ID NO:15 and SEQID NO:16. In one embodiment, the isolated nucleic acid moleculecomprises at least two CDRs. In another embodiment, the isolated nucleicacid molecule comprises three CDRs.

One aspect of the invention features an isolated nucleic acid moleculecomprising the nucleotide sequences shown in SEQ ID NOs: 11-16.

One aspect of the invention features a recombinant expression vectorcomprising the nucleic acid molecules of the invention. In oneembodiment, a recombinant expression vector comprising a nucleic acidmolecule having a nucleotide sequence encoding the binding molecule ofthe invention is featured. In another embodiment, the invention featuresa host cell into which the recombinant expression vector of theinvention has been introduced. In another aspect the invention featuresa method for producing a binding molecule that binds human ILT3,comprising culturing the host cell of the invention in a culture mediumuntil a binding molecule that binds human ILT3 is produced by the cell.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph demonstrating that monocyte-derived dendritic cells(MDDCs) differentiated in the presence of 9B11 exhibit a lowerexpression of cell surface co-stimulatory molecules, such as CD86, CD80,CD83 and HLA-DR, as measured by flow cytometry.

FIG. 2 is a graph demonstrating that MDDCs were unable to generate anallogenic T cell response in a mixed lymphocyte reaction.

FIG. 3 is a graph that demonstrates that MDDCs cultured in the presenceof 9B11 are unable to produce IL-12, TNFα or IL-1α when stimulated withLPS.

FIG. 4 is a graph demonstrating that freshly isolated blood dendriticcells incubated with 9B11 were unable to fully upregulate the expressionof co-stimulatory molecules when a cocktail of cytokines (IL-6, IL-1β,TNFα, and PGE) are used to mature the cells.

FIG. 5 shows that addition of 9B11 to monocytes, induced by activatingan immunoreceptor tyrosine-based activation motif (ITAM) in CD32,inhibits Ca+2 flux.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides binding molecules that specifically bindto ILT3, e.g., human ILT3 (hILT3), on antigen presenting cells, such asfor example, monocytes, macrophages and dendritic cells (DC), e.g.,monocyte-derived dendritic cells (MDDC). The binding molecules of theinvention are characterized by binding to hILT3 with high affinity anddownmodulating immune responses in vitro, e.g., downmodulatingalloimmune responses; the production of inflammatory cytokines bydendritic cells, e.g., monocyte-derived dendritic cells (MDDC); theupregulation of costimulatory molecules by DC, e.g., MDDC; and/orcalcium flux in monocytes. In addition, the binding molecules upregulatethe expression of inhibitory receptors on dendritic cells, e.g.,immature dendritic cells. Surprisingly, these same binding moleculeswhich downmodulate immune responses in vitro, are immunostimulatory invivo.

Various aspects of the invention relate to binding molecules, andpharmaceutical compositions thereof, as well as nucleic acids encodingbinding molecules, recombinant expression vectors and host cells formaking such binding molecules. Methods of using a binding molecule ofthe invention to detect human ILT3 or to modulate human ILT3 activity,either in vitro or in vivo, are also encompassed by the invention.

In order that the present invention may be more readily understood,certain terms are first defined.

I. Definitions

The term “immunoglobulin-like transcript 3” (abbreviated herein as“ILT3” or “hILT3”, and also known as CD85k), as used herein, refers tothe human member of the immunoglobulin superfamily which is selectivelyexpressed by myeloid antigen presenting cells (APCs) such as monocytes,macrophages, and dendritic cells, e.g., monocyte-derived dendritic cellsdifferentiated in the presence of IL-10 or vitamin D₃. The ILT3 proteinis a transmembrane protein of 447 amino acids with a predicted molecularmass of ˜47 kD. The amino terminal portion of the ILT3 protein beginswith a hydrophobic signal peptide of 23 amino acids followed by anextracellular region composed of two C2 type immunoglobulin superfamilydomains. Each domain shows two characteristic cysteines that are 49 and50 residues apart from each other, flanked by conserved residues(Val-x-Leu/Ile-x-Cys and His/Tyr-x-Gly-x-Tyr-x-Cys-Tyr/Phe,respectively, where x is any amino acid). The putative transmembranedomain of ILT3 consists of 21 amino acids, followed by a longcytoplasmic region of 167 amino acids, which is characterized by thepresence of one Tyr-x-x-Val motif followed by two Tyr-x-x-Leu motifsspaced by 26 amino acid residues. These Tyr-x-x-Leu pairs and theirspacing are reminiscent of the Tyr-x-x-Leu motifs (also referred to asimmunoreceptor tyrosine-based inhibitory motifs or ITIMs) identified inKIRs (natural-killer cell Ig receptors) as binding sites for proteintyrosine phosphatase SHP-1.

The putative immunoreceptor tyrosine-based inhibitory motifs in thecytoplasmic region of ILT3 suggest an inhibitory function of ILT3. Assuch, ILT3 behaves as an inhibitory receptor when cross-linked to astimulatory receptor.

The nucleic acid sequence of human (hILT3) ILT3 is set forth in SEQ IDNO:17 and the amino acid sequence is set forth in SEQ ID NO:18.

The term “binding molecule” as used herein includes molecules thatcontain at least one antigen binding site that specifically binds toILT3. By “specifically binds” it is meant that the binding moleculesexhibit essentially background binding to non-ILT3 molecules. Anisolated binding molecule that specifically binds ILT3 may, however,have cross-reactivity to ILT3 molecules from other species.

The binding molecules of the invention may comprise an immunoglobulinheavy chain of any isotype (e.g., IgG, IgE, IgM, IgD, IgA, and IgY),class (e.g., IgG1, IgG2, IgG3, IgG4, IgA1 and IgA2) or subclass ofimmunoglobulin molecule. Binding molecules may have both a heavy and alight chain. As used herein, the term binding molecule also includes,antibodies (including full length antibodies), monoclonal antibodies(including full length monoclonal antibodies), polyclonal antibodies,multispecific antibodies (e.g., bispecific antibodies), human, humanizedor chimeric antibodies, and antibody fragments, e.g., Fab fragments,F(ab′) fragments, fragments produced by a Fab expression library,epitope-binding fragments of any of the above, and engineered forms ofantibodies, e.g., scFv molecules, so long as they exhibit the desiredactivity, e.g., binding to ILT3.

An “antigen” is an entity (e.g., a proteinaceous entity or peptide) towhich a binding molecule specifically binds.

The term “epitope” or “antigenic determinant” refers to a site on anantigen to which a binding molecule specifically binds. Epitopes can beformed both from contiguous amino acids or noncontiguous amino acidsjuxtaposed by tertiary folding of a protein. Epitopes formed fromcontiguous amino acids are typically retained on exposure to denaturingsolvents whereas epitopes formed by tertiary folding are typically loston treatment with denaturing solvents. An epitope typically includes atleast 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15 amino acids in aunique spatial conformation. Methods of determining spatial conformationof epitopes include, for example, X-ray crystallography and2-dimensional nuclear magnetic resonance. See, e.g., Epitope MappingProtocols in Methods in Molecular Biology, Vol. 66, G. E. Morris, Ed.(1996).

Binding molecules that recognize the same epitope can be identified in asimple immunoassay showing the ability of one antibody to block thebinding of another antibody to a target antigen, i.e., a competitivebinding assay. Competitive binding is determined in an assay in whichthe binding molecule being tested inhibits specific binding of areference binding molecule to a common antigen, such as ILT3. Numeroustypes of competitive binding assays are known, for example: solid phasedirect or indirect radioimmunoassay (RIA); solid phase direct orindirect enzyme immunoassay (EIA) sandwich competition assay (see Stahliet al., Methods in Enzymology 9:242 (1983)); solid phase directbiotin-avidin EIA (see Kirkland et al., J. Immunol. 137:3614 (1986));solid phase direct labeled assay, solid phase direct labeled sandwichassay (see Harlow and Lane, Antibodies: A Laboratory Manual, Cold SpringHarbor Press (1988)); solid phase direct label RIA using I-125 label(see Morel et al., Mol. Immunol. 25(1):7 (1988)); solid phase directbiotin-avidin EIA (Cheung et al., Virology 176:546 (1990)); and directlabeled RIA. (Moldenhauer et al., Scand. J. Immunol. 32:77 (1990)).Typically, such an assay involves the use of purified antigen bound to asolid surface or cells bearing either of these, an unlabeled testbinding molecule and a labeled reference binding molecule. Competitiveinhibition is measured by determining the amount of label bound to thesolid surface or cells in the presence of the test binding molecule.Usually the test binding molecule is present in excess. Usually, when acompeting binding molecule is present in excess, it will inhibitspecific binding of a reference binding molecule to a common antigen byat least 50-55%, 55-60%, 60-65%, 65-70% 70-75% or more.

An epitope is also recognized by immunologic cells, for example, B cellsand/or T cells. Cellular recognition of an epitope can be determined byin vitro assays that measure antigen-dependent proliferation, asdetermined by ³H-thymidine incorporation, by cytokine secretion, byantibody secretion, or by antigen-dependent killing (cytotoxic Tlymphocyte assay).

The term “monoclonal binding molecule” as used herein refers to abinding molecule obtained from a population of substantially homogeneousbinding molecules. Monoclonal binding molecules are highly specific,being directed against a single antigenic site. Furthermore, in contrastto polyclonal binding molecule preparations which typically includedifferent binding molecules directed against different determinants(epitopes), each monoclonal binding molecule is directed against asingle determinant on the antigen. The modifier “monoclonal” indicatesthe character of the binding molecule as being obtained from asubstantially homogeneous population of binding molecules, and is not tobe construed as requiring production of the binding molecule by anyparticular method. For example, the monoclonal binding molecules to beused in accordance with the present invention may be made by thehybridoma method first described by Kohler, et al., Nature 256:495(1975), or may be made by recombinant DNA methods (see, e.g., U.S. Pat.No. 4,816,567). The “monoclonal binding molecules” may also be isolatedfrom phage antibody libraries using the techniques described inClackson, et al., Nature 352:624-628 (1991) and Marks et al., J. MolBiol. 222:581-597 (1991), for example.

The term “chimeric binding molecule” refers to a binding moleculecomprising amino acid sequences derived from different species. Chimericbinding molecules can be constructed, for example by geneticengineering, from binding molecule gene segments belonging to differentspecies.

The monoclonal binding molecules herein specifically include “chimeric”binding molecules in which a portion of the heavy and/or light chain isidentical with or homologous to corresponding sequences in bindingmolecules derived from a particular species or belonging to a particularantibody class or subclass, while the remainder of the chain(s) isidentical with or homologous to corresponding sequences in bindingmolecules derived from another species or belonging to another antibodyclass or subclass, as well as fragments of such binding molecules, solong as they exhibit the desired biological activity (U.S. Pat. No.4,816,567; and Morrison, et al., Proc. Natl. Acad. Sci. USA 81:6851-6855(1984)). e.g., binding to human ILT3 (hILT3).

Both the light and heavy chains are divided into regions of structuraland functional homology. The terms “constant” and “variable” are usedfunctionally. In this regard, it will be appreciated that the variabledomains of both the light (VL) and heavy (VH) chain portions determineantigen recognition and specificity. Conversely, the constant domains ofthe light chain (CL) and the heavy chain (CH1, CH2 or CH3) conferimportant biological properties such as secretion, transplacentalmobility, Fc receptor binding, complement binding, and the like. Byconvention the numbering of the constant region domains increases asthey become more distal from the antigen binding site or amino-terminusof the antibody. The N-terminus is a variable region and at theC-terminus is a constant region; the CH3 and CL domains actuallycomprise the carboxy-terminus of the heavy and light chain,respectively.

A “variable region” when used in reference to a binding molecule refersto the amino terminal portion of a binding molecule which confersantigen binding onto the molecule and which is not the constant region.The term includes complementarity determining regions and frameworkregions. The term also includes functional fragments thereof whichmaintain some or all of the binding function of the whole variableregion.

The term “hypervariable region” when used herein refers to the regionsof a binding molecule variable domain which are hypervariable insequence and/or form structurally defined loops. The hypervariableregion comprises amino acid residues from a “complementarity determiningregion” or “CDR”.

As used herein, the term “CDR” or “complementarity determining region”means the noncontiguous antigen combining sites found within thevariable region of both heavy and light chain polypeptides. Theseparticular regions have been described by Kabat, et al., J. Biol. Chem.252, 6609-6616 (1977) and Kabat, et al., Sequences of protein ofimmunological interest. (1991), and by Chothia, et al., J. Mol. Biol.196:901-917 (1987) and by MacCallum, et al., J. Mol. Biol. 262:732-745(1996) where the definitions include overlapping or subsets of aminoacid residues when compared against each other. Preferably, the Kabatdefinition is used to describe a CDR of a binding molecule of theinvention. Nevertheless, application of either definition to refer to aCDR of a binding molecule or grafted binding molecule or variantsthereof is within the scope of the term as defined and used herein.

As used herein, the term “framework region” or “FR” means each domain ofthe framework that is separated by the CDRs. Therefore, a variableregion framework is between about 100-120 amino acids in length butrefers only those amino acids outside of the CDRs.

“Humanized” forms of non-human (e.g., murine) binding molecules arechimeric antibodies which contain minimal sequence derived fromnon-human binding molecule. For the most part, humanized bindingmolecules are human binding molecules (acceptor/recipient bindingmolecule) in which residues from a hyper-variable region are replaced byresidues from a hypervariable region of a non-human species (donorbinding molecule) such as mouse, rat, rabbit or nonhuman primate havingthe desired specificity, affinity, and capacity. In some instances, Fvframework region (FR) residues of the human binding molecule arealtered, e.g., replaced by, substituted, or backmutated to correspondingnon-human residues. Furthermore, humanized binding molecules maycomprise residues which are not found in the recipient binding moleculeor in the donor binding molecule. These modifications are generally madeto further refine binding molecule performance. In general, thehumanized binding molecule will comprise substantially all of at leastone, and typically two, variable domains, in which all or substantiallyall of the hypervariable loops correspond to those of a non-humanbinding molecule and all or substantially all of the FR regions arethose of a human binding molecule sequence. The humanized bindingmolecule optionally also will comprise at least a portion of a bindingmolecule constant region (Fc), typically that of a human bindingmolecule. For further details, see Jones, et al., Nature 321:522-525(1986); Riechmann, et al., Nature 332:323-329 (1988); and Presta, Curr.Op. Struct. Biol. 2:593-596 (1992).

Preferably, a humanized binding molecule of the invention comprises atleast one CDR selected from the group consisting of SEQ ID NO:3(GFAFSSYDMS(VH CDR1)), SEQ ID NO:4 (TISSSGSYTYYPDSVKG (VH CDR2)), SEQ IDNO:5 (LWGAMDY (VH CDR3)), SEQ ID NO:6 (RASQGLTNDLH (VL CDR1)), SEQ IDNO:7 (YASQSIS (VL CDR2)), and SEQ ID NO:8 (QQSNSWPFT (VL CDR3)).

The term “engineered” or “recombinant” binding molecule, as used hereinincludes binding molecules that are prepared, expressed, created orisolated by recombinant means, such as binding molecules expressed usinga recombinant expression vector transfected into a host cell, bindingmolecules isolated from a recombinant, combinatorial binding moleculelibrary, binding molecules isolated from an animal (e.g., a mouse) thatis transgenic for human immunoglobulin genes (see e.g., Taylor, L. D.,et al. (1992) Nucl. Acids Res. 20:6287-6295) or binding moleculesprepared, expressed, created or isolated by any other means thatinvolves splicing of human binding molecule gene sequences to other DNAsequences. In certain embodiments, however, such recombinant humanbinding molecules are subjected to in vitro mutagenesis (or, when ananimal transgenic for human Ig sequences is used, in vivo somaticmutagenesis) and thus the amino acid sequences of the VH and VL regionsof the recombinant binding molecules are sequences that, while derivedfrom and related to human germline VH and VL sequences, may notnaturally exist within the human binding molecule germline repertoire invivo.

An “isolated binding molecule”, as used herein, refers to a bindingmolecule that is substantially free of other binding molecules havingdifferent antigenic specificities (e.g., an isolated binding moleculethat specifically binds ILT3 is substantially free of binding moleculesthat specifically bind antigens other than ILT3). Moreover, an isolatedbinding molecule may be substantially free of other cellular materialand/or chemicals. An “isolated” binding molecule is one which has beenidentified and separated and/or recovered from a component of itsnatural environment. Contaminant components of its natural environmentinclude, e.g., materials which would interfere with diagnostic ortherapeutic uses for the binding molecule, and may include enzymes,hormones, and other proteinaceous or nonproteinaceous solutes. Inpreferred embodiments, the binding molecule will be purified (1) togreater than 95% by weight of binding molecule as determined by the

Lowry method, and most preferably more than 99% by weight, (2) to adegree sufficient to obtain at least 15 residues of N-terminal orinternal amino acid sequence by use of a spinning cup sequenator, or (3)to homogeneity by SDS-PAGE under reducing or nonreducing conditionsusing Coomassie blue or, preferably, silver stain. Isolated bindingmolecules include binding molecules in situ within recombinant cellssince at least one component of the binding molecule's naturalenvironment will not be present. Ordinarily, however, isolated bindingmolecules will be prepared by at least one purification step.

As used herein the term “binding constant” “(kd)”, also referred to as“affinity constant”, is a measure of the extent of a reversibleassociation between two molecular species includes both the actualbinding affinity as well as the apparent binding affinity. The actualbinding affinity is determined by calculating the ratio of the Kassoc inM⁻¹S⁻¹ to the Kdissoc in S⁻¹ and has the units “M⁻¹”. Therefore,conferring or optimizing binding affinity includes altering either orboth of these components to achieve the desired level of bindingaffinity. The apparent affinity can include, for example, the avidity ofthe interaction. For example, a bivalent heteromeric variable regionbinding fragment can exhibit altered or optimized binding affinity dueto its valency. Binding affinity can be determined by measurement ofsurface plasmon resonance, e.g., using a BIAcore system.

The term “nucleic acid molecule”, as used herein, includes DNA moleculesand RNA molecules. A nucleic acid molecule may be single-stranded ordouble-stranded, but preferably is double-stranded DNA.

The term “isolated nucleic acid molecule”, as used herein in referenceto nucleic acids encoding binding molecules that bind ILT3, refers to anucleic acid molecule in which the nucleotide sequences encoding thebinding molecule are free of other nucleotide sequences which othersequences may naturally flank the nucleic acid in human genomic DNA.These sequences may optionally include 5′ or 3′nucleotide sequencesimportant for regulation or protein stability.

The term “vector”, as used herein, refers to a nucleic acid moleculecapable of transporting another nucleic acid to which it has beenlinked. One type of vector is a “plasmid”, which refers to a circulardouble stranded DNA loop into which additional DNA segments may beligated. Another type of vector is a viral vector, wherein additionalDNA segments may be ligated into the viral genome. Certain vectors arecapable of autonomous replication in a host cell into which they areintroduced (e.g., bacterial vectors having a bacterial origin ofreplication and episomal mammalian vectors). Other vectors (e.g.,non-episomal mammalian vectors) can be integrated into the genome of ahost cell upon introduction into the host cell, and thereby arereplicated along with the host genome. Moreover, certain vectors arecapable of directing the expression of genes to which they areoperatively linked. Such vectors are referred to herein as “recombinantexpression vectors” (or simply, “expression vectors”). In general,expression vectors of utility in recombinant DNA techniques are often inthe form of plasmids. In the present specification, “plasmid” and“vector” may be used interchangeably as the plasmid is the most commonlyused form of vector. However, the invention includes such other forms ofexpression vectors, such as viral vectors (e.g., replication defectiveretroviruses, adenoviruses and adeno-associated viruses), which serveequivalent functions.

The term “recombinant host cell” (or simply “host cell”), as usedherein, refers to a cell into which a recombinant expression vector hasbeen introduced. It should be understood that such terms are intended torefer not only to the particular subject cell but to the progeny of sucha cell. Because certain modifications may occur in succeedinggenerations due to either mutation or environmental influences, suchprogeny may not, in fact, be identical to the parent cell, but are stillincluded within the scope of the term “host cell” as used herein.

As used herein, the term “T cell” (i.e., T lymphocyte) is includes cellswithin the T cell lineage, including thymocytes, immature T cells,mature T cells and the like, from a mammal (e.g., human). Preferably, Tcells are mature T cells that express either CD4 or CD8, but not both,and a T cell receptor. The various T cell populations described hereincan be defined based on their cytokine profiles and their function.

As used herein, a “professional antigen presenting cell” or “APC” is acell that can present antigen in a form in which it can be recognized bycells. The cells that can “present” antigen include B cells, monocytes,macrophages and dendritic cells.

As used herein, the term “dendritic cell” or “DC” includes APCs capableof activating naïve T cells and stimulating the growth anddifferentiation of B cells. DCs are lineage negative cells, i.e., theylack cell surface markers for T cells, B cells, NK cells, andmonocytes/macrophages, however they strongly express variouscostimulatory molecules (e.g., CD86, CD80, CD83, and HLA-DR) and/oradhesion molecules. Dendritic cells can be subdivided into two main celltypes, namely “myeloid-derived dendritic cells” (“MDDC”) and“plasmacytoid-derived dendritic cells” (“PDDC”). Cell surface markers,such as ILT3, can be used to distinguish the two dendritic celllineages, as can the limited proliferative ability of PDDC. See, forexample, Santiago-Schwartz, F. (2004) Rheum. Dis. Clin. Noth Am.30:115-134, incorporated herein by reference. Furthermore, DCs can alsobe divided into “immature DCs” and “mature DCs”. Immature DCs arespecialized in antigen capture and processing, whereas mature DCspresent antigen and have an increased T-cell stimulatory capacity.Immature DCs can be matured using art recognized techniques, such asculturing in the presence of an inflammatory cytokine cocktail.

As used herein, the term “naïve T cells” includes T cells that have notbeen exposed to cognate antigen and so are not activated or memorycells. Naive T cells are not cycling and human naïve T cells areCD45RA+. If naïve T cells recognize antigen and receive additionalsignals depending upon but not limited to the amount of antigen, routeof administration and timing of administration, they may proliferate anddifferentiate into various subsets of T cells, e.g. effector T cells.

As used herein, the term “memory T cell” includes lymphocytes which,after exposure to antigen, become functionally quiescent and which arecapable of surviving for long periods in the absence of antigen. Humanmemory T cells are CD45RA−.

As used herein, the term “effector T cell” or “Teff cell” includes Tcells which function to eliminate antigen (e.g., by producing cytokineswhich modulate the activation of other cells or by cytotoxic activity).The term “effector T cell” includes T helper cells (e.g., Th1 and Th2cells) and cytotoxic T cells. Th1 cells mediate delayed typehypersensitivity (DTH) responses and macrophage activation (e.g.,cellular immune responses) while Th2 cells provide help to B cells andare critical in the allergic response (e.g., humoral immune responses)(Mosmann and Coffman, 1989, Annu. Rev. Immunol. 7, 145-173; Paul andSeder, 1994, Cell 76, 241-251; Arthur and Mason, 1986, J. Exp. Med. 163,774-786; Paliard, et al., 1988, J. Immunol. 141, 849-855; Finkelman, etal., 1988, J. Immunol. 141, 2335-2341).

As used herein, the term “ T helper type 1 response” (Th1 response)refers to a response that is characterized by the production of one ormore cytokines selected from IFN-γ, IL-2, TNF, and lymphotoxin (LT) andother cytokines produced preferentially or exclusively by Th1 cellsrather than by Th2 cells. As used herein, a “T helper type 2 response”(Th2 response) refers to a response by CD4+ T cells that ischaracterized by the production of one or more cytokines selected fromIL-4, IL-5, IL-6 and IL-10, and that is associated with efficient B cell“help” provided by the Th2 cells (e.g., enhanced IgG1 and/or IgEproduction).

As used herein, the term “regulatory T cell” or “Treg cell” includes Tcells which produce low levels of IL-2, IL-4, IL-5, and IL-12.Regulatory T cells produce TNFα, TGFβ, IFN-γ, and IL-10, albeit at lowerlevels than effector T cells. Although TGFβ is the predominant cytokineproduced by regulatory T cells, the cytokine is produced at levels lessthan or equal to that produced by Th1 or Th2 cells, e.g., an order ofmagnitude less than in Th1 or Th2 cells. Regulatory T cells can be foundin the CD4+CD25+ population of cells (see, e.g., Waldmann and Cobbold.2001. Immunity. 14:399). Regulatory T cells actively suppress theproliferation and cytokine production of Th1, Th2, or naïve T cellswhich have been stimulated in culture with an activating signal (e.g.,antigen and antigen presenting cells or with a signal that mimicsantigen in the context of MHC, e.g., anti-CD3 antibody, plus anti-CD28antibody).

As used herein, the term “anergy” or “tolerance” includes refractivityto activating receptor-mediated stimulation. Such refractivity isgenerally antigen-specific and persists after exposure to the tolerizingantigen has ceased. For example, tolerance is characterized by lack ofcytokine production, e.g., IL-2. Tolerance occurs when cells are exposedto antigen and receive a first signal (a T cell receptor or CD-3mediated signal) in the absence of a second signal (a costimulatorysignal) or by modulation, e.g., upmodulation of an inhibitory signalfrom an inhibitory receptor, such as, for example, ILT3. Under theseconditions, reexposure of the cells to the same antigen (even ifreexposure occurs in the presence of a costimulatory polypeptide)results in failure to produce cytokines and, thus, failure toproliferate. For example, tolerance is characterized by lack of cytokineproduction, e.g., IL-2, or can be assessed by use of a mixed lymphocyteculture assay. Tolerance can occur to self antigens or to foreignantigens.

As used herein, the term “inhibitory signal” refers to a signaltransmitted via an inhibitory receptor (e.g., ILT3), e.g., on an immunecell, such as a DC, e.g., MDDC. Such a signal antagonizes a signal viaan activating receptor (e.g., via a TCR, CD3, BCR, or Fc polypeptide).Transduction of a signal via an inhibitory receptor results in“downmodulation of immune cell activation” in vitro. Transmission of aregulatory signal which can result in, e.g., inhibition of secondmessenger generation; an inhibition of proliferation; an inhibition ofeffector function in the immune cell, e.g., reduced phagocytosis,reduced antibody production, reduced cellular cytotoxicity, the failureof the immune cell to produce mediators, (such as cytokines (e.g., IL-2)and/or mediators of allergic responses); or the development oftolerance.

In one embodiment, downmodulation of immune cell activation in vitrodownmodulates an alloimmune response. As used herein, an “alloimuneresponse” refers to an immune response that occurs between antigenicallydistinct cells. An allommune response can be measured utilizing a “mixedlymphocyte culture or reaction” (“MLC” or “MLR”) which is a type oflymphocyte proliferation test in which lymphocytes, i.e., restinglymphocytes, i.e., lymphocytes that have not been stimulated, from twoindividuals (a stimulator and a responder), i.e., allogenic lymphocytes,are cultured together and the proliferative response (“mixed lymphocytereaction”) is measured by ³H-labeled thymidine uptake and/or cytokineproduction. In one embodiment, the MLC is a primary MLC, i.e., respondercells are mixed with stimulator cells at, which may or may not have beeninactivated by, e.g., gamma irradiation and cultured for, e.g., 3 days.In another embodiment, the MLC is a secondary MLC, i.e., responder cellsare initially cultured in a primary MLC with stimulator cells which mayor may not have been inactivated by, e.g., gamma irradiation at, andsubsequently viable cells are recovered and restimulated with newstimulators cells, which may or may not have been inactivated by, e.g.,gamma irradiation, and cultured for an additional, e.g., 3, 4, 5, 6, 7days.

In another embodiment, downmodulation of immune cell activation resultsin downmodulation of the expression of costimulatory molecules on acell, e.g., a dendritic cell, or a dampening in an increase incostimulatory molecule expression. In yet another embodiment,downmodulation of immune cell activation in vitro results indownmodulation of intracellular calcium flux.

In one embodiment, the activation state of MDDC is downmodulated invitro. In one embodiment, MDDC are derived from monocytes cultured inthe presence of, e.g., GM-CSF and IL-4 added on, e.g., days zero andthree. In one embodiment, MDDC are derived from monocytes cultured inthe presence of a binding molecule of the invention added on, e.g., dayszero and three. In another embodiment the activation state of maturedendritic cells is downmodulated. In one embodiment, mature dendriticcells are derived from blood dendritic cells cultured in the presenceof, e.g., IL-6, IL-1 beta, TNF-alpha, and PGE added on, e.g., day one.In another embodiment the activation state of monocytes isdownmodulated.

As used herein “upmodulation of an immune response” refers to anincrease in a T cell mediated and/or B cell mediated immune response invivo. Exemplary immune responses include T cell responses, e.g.,cytokine production, and cellular cytotoxicity. In addition, the termimmune response includes antibody production (humoral responses) andactivation of cells of the innate immune system, e.g.,cytokineresponsive cells such as macrophages.

As used herein, the various forms of the term “modulate” includestimulation (e.g., increasing, upmodulating, or upregulating aparticular response or activity) and inhibition (e.g., decreasing,downmodulating, or downregulating a particular response or activity).

“Treatment” refers to both therapeutic treatment and prophylactic orpreventative measures. Those in need of treatment may include thosealready having a disorder as well as those which do not yet have adisorder.

A “disorder” is any condition that would benefit from treatment with thebinding molecules of the present invention. This includes chronic andacute disorders or diseases or pathological conditions associated withimmune responses that are too high or too low.

Various aspects of the invention are described in further detail in thefollowing subsections.

II. ILT3 Binding Molecules

The present invention provides isolated ILT3 binding molecules.Exemplary binding molecules of the present invention include the 9B11antibody, or a binding portion thereof. The 9B11 antibody is ananti-ILT3 antibody that binds to ILT3 on APC, e.g., monocytes,macrophages, dendritic cells, e.g., MDDC, e.g., human cells, with highaffinity. The binding molecules of the invention are characterized bybinding to hILT3 with high affinity and downmodulating immune responsesin vitro, e.g., downmodulating alloimmune responses; the production ofinflammatory cytokines by dendritic cells, e.g., monocyte-deriveddendritic cells (MDDC); the upregulation of costimulatory molecules byDC, e.g., MDDC; and/or calcium flux in monocytes. In addition, thebinding molecules upregulate the expression of inhibitory receptors ondendritic cells, e.g., immature dendritic cells. Surprisingly, thesesame binding molecules which downmodulate immune responses in vitro, areimmunostimulatory in vivo. For example, the binding molecules stimulateimmune responses in vivo such as cellular immune responses, e.g., DTHresponses.

In one embodiment, the VH domain of a binding molecule of the inventioncomprises the amino acid sequence set forth in SEQ ID NO:1.(MEFGLSLVFLVLILKGVQCEVKLVESGGDLVKPGGSLKLSCAASGFAFSSYDMSWVRQTPEKRLEWVATISSSGSYTYYPDSVKGRFTISRDNARNTLYLQMSSLRSEDTALYYCERLWGAMDYWGQGTLVTVSS) (9B11 VH domain, including leader)). Itwill be understood that although some of the sequences of bindingmolecules described herein include leader sequences, a binding moleculeof the invention may also exclude the leader sequence; which isoptional. For example, in one embodiment, a binding molecule of theinvention comprises the amino acid sequence of the mature protein shownin SEQ ID NO:1. e.g., amino acids 20-135 of SEQ ID NO:1.

In one embodiment, a VL domain of a binding molecule of the inventioncomprises the amino acid sequence set forth in SEQ ID NO:2.(METDTILLWVLLLWVPGSTGDIVLTQSPATLSVTPGDSVSLSCRASQGLTNDLHWYQQKPHESPRLLIKYASQSISGIPSRFSGSGSGTDFTLTINSVETEDFGVFFCQQSNSWPFTFGAGTKLEIK) (9B11 VL domain, including leader)).

In one embodiment, a VH domain of a binding molecule of the inventioncomprises amino acid residues 20-138 of SEQ ID NO.:1.(EVKLVESGGDLVKPGGSLKLSCAASGFAFSSYDMSWVRQTPEKRLEWVATISSSGSYTYYPDSVKGRFTISRDNARNTLYLQMSSLRSEDTALYYCERLWGAM DYWGQGTLVTVSS)(9B11 VH domain, without leader)).

In one embodiment, a VL domain of a binding molecule of the inventioncomprises amino acid residues 21-127 of SEQ ID NO.:2.(DIVLTQSPATLSVTPGDSVSLSCRASQGLTNDLHWYQQKPHESPRLLIKYASQSISGIPSRFSGSGSGTDFTLTINSVETEDFGVFFCQQSNSWPFTFGAGTKLEIK) (9B11 VL domain,without leader)).

In one embodiment of the invention a VL chain comprises a leader and/orsignal sequence, i.e., amino acid residues 1-20 of SEQ ID NO:2 (SEQ IDNO:21). In one embodiment, the VH chain comprises a leader and/or signalsequence, i.e., amino acid residues 1-19 of SEQ ID NO:1 (SEQ ID NO:22).

In one embodiment, a binding molecule of the invention comprises a VHdomain comprising a CDR set forth in SEQ ID NO:3. (9B11 VH CDR1).

In one embodiment, a binding molecule of the invention comprises a VHdomain comprising a CDR set forth in SEQ ID NO:4. (9B11 VH CDR2).

In one embodiment, a binding molecule of the invention comprises a VHdomain comprising a CDR set forth in SEQ ID NO:5. (9B11 VH CDR3).

In one embodiment, a binding molecule of the invention comprises a VLdomain comprising a CDR set forth in SEQ ID NO:6. (9B11 VL CDR1).

In one embodiment, a binding molecule of the invention comprises a VLdomain comprising a CDR set forth in SEQ ID NO:7. (9B11 VL CDR2).

In one embodiment, a binding molecule of the invention comprises a VLdomain comprising a CDR set forth in SEQ ID NO:8. (9B11 VL CDR3).

The invention also pertains to nucleic acid molecules encoding the aboveamino acid sequences.

In one embodiment, a VH domain of a binding molecule of the inventioncomprises the nucleotide sequence set forth in SEQ ID NO:9. (9B11 VHdomain, including leader).

In one embodiment, a VH domain of a binding molecule of the inventioncomprises nucleotides 58-405 of SEQ ID NO.:9. (9B11 VH domain, withoutleader).

In one embodiment, the a VL domain of a binding molecule of theinvention comprises the nucleotide sequence set forth in SEQ ID NO:10.(9B11 VL domain, including leader).

In one embodiment, the a VL domain of a binding molecule of theinvention comprises nucleotides 61-383 of SEQ ID NO.:10. (9B11 VLdomain, without leader).

In one embodiment, a binding molecule of the invention comprises a VHdomain comprising a CDR the nucleic acid sequence of which is set forthin SEQ ID NO:11. (9B11 VH CDR1).

In one embodiment, a binding molecule of the invention comprises a VHdomain comprising a CDR the nucleic acid sequence of which is set forthin SEQ ID NO:12. (9B11 VH CDR2).

In one embodiment, a binding molecule of the invention comprises a VHdomain comprising a CDR the nucleic acid sequence of which is set forthin SEQ ID NO:13. (9B11 VH CDR3).

In one embodiment, a binding molecule of the invention comprises a VLdomain comprising a CDR the nucleic acid sequence of which is set forthin SEQ ID NO:14. (9B11 VL CDR1).

In one embodiment, a binding molecule of the invention comprises a VLdomain comprising a CDR the nucleic acid sequence of which is set forthin SEQ ID NO:15. (9B11 VL CDR2).

In one embodiment, a binding molecule of the invention comprises a VLdomain comprising a CDR the nucleic acid sequence of which is set forthin SEQ ID NO:16. (9B11 VL CDR3).

In one embodiment, the a CL domain of a binding molecule of theinvention comprises the amino acid sequence set forth in SEQ ID NO:23.(Murine IgG2a light chain constant region).

In one embodiment, the a CH domain of a binding molecule of theinvention comprises the amino acid sequence set forth in SEQ ID NO:24.(Murine IgG2a heavy chain constant region).

In one embodiment, a binding molecule of the invention comprises theamino acid sequence set forth in SEQ ID NO:25. (Chimeric 9B11 VL/humanCL IgG1).

In one embodiment, a binding molecule of the invention comprises theamino acid sequence set forth in SEQ ID NO:26. (Chimeric 9B11 VH/humanGly-CH IgG1).

In one embodiment, a binding molecule of the invention comprises theamino acid sequence set forth in SEQ ID NO:27. (Chimeric 9B11 VH/humanAgly-CH IgG1).

In one embodiment, a binding molecule of the invention comprises theamino acid sequence set forth in SEQ ID NO:28. (Humanized 9B11 VL).

In one embodiment, a binding molecule of the invention comprises theamino acid sequence set forth in SEQ ID NO:29. (Humanized 9B11 VH).

In one embodiment, the a CL domain of a binding molecule of theinvention comprises the amino acid sequence set forth in SEQ ID NO:30.(Human IgG1 Gly heavy chain constant region).

In one embodiment, the a CH domain of a binding molecule of theinvention comprises the amino acid sequence set forth in SEQ ID NO:31.(Human IgG1 Agly heavy chain constant region).

In one embodiment, the a CL domain of a binding molecule of theinvention comprises the amino acid sequence set forth in SEQ ID NO:32.(Human IgG1 light chain constant region).

In one embodiment, a binding molecule of the invention comprises theamino acid sequence set forth in SEQ ID NO:33. (Complete Humanized 9B11Light).

In one embodiment, a binding molecule of the invention comprises theamino acid sequence set forth in SEQ ID NO:34. (Complete Humanized 9B11Heavy-Gly).

In one embodiment, a binding molecule of the invention comprises theamino acid sequence set forth in SEQ ID NO:35. (Complete Humanized 9B11Heavy-Agly).

In one embodiment, a binding molecule of the invention has the VL aminoacid sequence of the 9B11 VL region as set forth in SEQ ID NO: 2 and theVH amino acid sequence of the 9B11 VH region as set forth in SEQ IDNO: 1. In another embodiment, a binding molecule of the invention has LCand HC sequences as set forth in SEQ ID NOs:23 and 24, respectively;

(SEQ ID NO: 23) ADAAPTVSIFPPSSEQLTSGGASVVCFLNNFYPKDINVKWKIDGSERQNGVLNSWTDQDSKDSTYSMSSTLTLTKDEYERHNSYTCEATHKTSTSPIVKS FNRNE;(SEQ ID NO: 24) AKTTPPSVYPLAPGCGDTTGSSVTLGCLVKGYFPESVTVTWNSGSLSSSVHTFPALLQSGLYTMSSSVTVPSSTWPSQTVTCSVAHPASSTTVDKKLEPSGPISTINPCPPCKECKCPAPNLEGGPSVFIFPPNIKDVLMISLTPKVTCVVVDVSEDDPDVQISWFVNNVEVHTAQTQTHREDYNSTIRVVSTLPIQHQDWMSGKEFKCKVNNKDLPSPIERTISKIKGLVRAQVYILPPPAEQLSRKDVSLTCLVVGFNPGDISVEWTSNGHTEENYKDTAPVLDSDGSYFIYSKLNMKTSKWEKTDSFSCNVRHEGLKNYYLKKTISRSPGK.

In one embodiment of the invention the VL chain comprises a leaderand/or signal sequence, e.g., amino acid residues 1-20 of SEQ ID NO:2.In one embodiment, the VH chain comprises a leader and/or signalsequence, e.g., amino acid residues 1-19 of SEQ ID NO:1. In anotherembodiment, a binding molecule of the invention does not comprise aleader and/or signal sequence.

In one aspect, the invention pertains to 9B11 binding molecules andother binding molecules with equivalent properties to 9B11, such asbinding to hILT3 with high affinity and downmodulate immune responses invitro, e.g., downmodulate alloimmune responses; the production ofinflammatory cytokines by dendritic cells, e.g., monocyte-deriveddendritic cells (MDDC); the upregulation of costimulatory molecules byDC, e.g., MDDC; and/or calcium flux in monocytes; and upregulate theexpression of inhibitory receptors on dendritic cells, e.g., immaturedendritic cells and stimulating immune response in vivo, such as a Th1immune responses. Accordingly, equivalent binding molecules of theinvention e.g., generate a negative signal in a cell via ILT3 or blockgeneration of a stimulatory signal via an activating receptor in vitro,while they are immunostimulatory in vivo, e.g., they sequester ordownmodulate ILT3 to prevent its association with an activatingreceptor, thereby preventing the downmodulation of an immune response.

In one embodiment, the invention provides an isolated human bindingmolecule with a light chain variable region (VL) comprising the aminoacid sequence of SEQ ID NO: 2, and optionally a leader sequence, and aheavy chain variable region (VH) comprising the amino acid sequence ofSEQ ID NO: 1, and optionally a leader sequence. In certain embodimentsof the invention, the binding molecules of the invention comprise aheavy chain constant region, such as an IgG1, IgG2, IgG3, IgG4, IgA,IgE, IgM or IgD constant region. Furthermore, the binding molecule cancomprise a light chain constant region, either a kappa light chainconstant region or a lambda light chain constant region. Preferably, thebinding molecule comprises a kappa light chain constant region.

In one embodiment, a binding molecule of the invention comprises a lightchain constant region as set forth in SEQ ID NO:23. In one embodiment, abinding molecule of the invention comprises a heavy chain constantregion as set forth in SEQ ID NO:24. In one embodiment, a bindingmolecule of the invention comprises a heavy chain constant region as setforth in SEQ ID NO:30. In one embodiment, a binding molecule of theinvention comprises a heavy chain constant region as set forth in SEQ IDNO:31. In one embodiment, a binding molecule of the invention comprisesa light chain constant region as set forth in SEQ ID NO:32.

In another embodiment, the invention provides a binding molecule having9B11-related VL CDR domains, for example, a binding molecule with alight chain variable region (VL) having at least one CDR domaincomprising an amino acid sequence selected from the group consisting ofSEQ ID NO: 6, SEQ ID NO: 7, and SEQ ID NO: 8. In another embodiment, alight chain variable region (VL) has at least two CDR domains comprisingan amino acid sequence selected from the group consisting of SEQ ID NO:6, SEQ ID NO: 7, and SEQ ID NO: 8. In yet another embodiment, a lightchain variable region (VL) has CDR domains comprising the amino acidsequences consisting of SEQ ID NO: 6, SEQ ID NO: 7, and SEQ ID NO: 8.

In still other embodiments, the invention provides a binding moleculehaving 9B11-related VH CDR domain, for example, a binding molecule witha heavy chain variable region (VH) having at least one CDR domaincomprising an amino acid sequence selected from the group consisting ofSEQ ID NO: 3, SEQ ID NO: 4, and SEQ ID NO: 5. In another embodiment, aheavy chain variable region (VH) has at least two CDR domains comprisingan amino acid sequence selected from the group consisting of SEQ ID NO:3, SEQ ID NO: 4, and SEQ ID NO: 5. In yet another embodiment, a heavychain variable region (VH) has CDR domains comprising the amino acidsequences consisting of SEQ ID NO: 3, SEQ ID NO: 4, and SEQ ID NO: 5.

In another embodiment, a binding molecule of the invention comprises atleast one CDR derived from a murine anti-human ILT3 binding molecule,e.g., a 9B11 binding molecule. As used herein the term “derived from” adesignated protein refers to the origin of the polypeptide. In oneembodiment, the polypeptide or amino acid sequence which is derived froma particular starting polypeptide is a CDR sequence or sequence relatedthereto. In another embodiment, the polypeptide or amino acid sequencewhich is derived from a particular starting polypeptide is a FR sequenceor sequence related thereto. In one embodiment, the amino acid sequencewhich is derived from a particular starting polypeptide is notcontiguous.

For example, in one embodiment, one, two, three, four, five, or six CDRsare derived from a murine 9B11 antibody. In one embodiment, a bindingmolecule of the invention comprises at least one heavy or light chainCDR of a murine 9B11 antibody. In another embodiment, a binding moleculeof the invention comprises at least two CDRs from a murine 9B11antibody. In another embodiment, a binding molecule of the inventioncomprises at least three CDRs from a murine 9B11 antibody. In anotherembodiment, a binding molecule of the invention comprises at least fourCDRs from a murine 9B11 antibody. In another embodiment, a bindingmolecule of the invention comprises at least five CDRs from a murine9B11 antibody. In another embodiment, a binding molecule of theinvention comprises at least six CDRs from a murine 9B11 antibody.

It will also be understood by one of ordinary skill in the art that abinding molecule of the invention may be modified such that they vary inamino acid sequence from the 9B11 molecule from which they were derived.For example, nucleotide or amino acid substitutions leading toconservative substitutions or changes at “non-essential” amino acidresidues may be made (e.g., in CDR and/or framework residues) andmaintain the ability to bind to ILT3, e.g., human ILT3.

In one embodiment, a binding molecule of the invention comprises apolypeptide or amino acid sequence that is essentially identical to thatof a 9B11 antibody, or a portion thereof wherein the portion consists ofat least 3-5 amino acids, of at least 5-10 amino acids, at least 10-20amino acids, at least 20-30 amino acids, or at least 30-50 amino acids,or which is otherwise identifiable to one of ordinary skill in the artas having its origin in the starting sequence.

In another embodiment, a VL region of a binding molecule of theinvention shares an amino acid sequence identity that is about 80%, 85%,86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, tothat of a 9B11 VL region wherein the portion consists of at least 3-5amino acids, of at least 5-10 amino acids, at least 10-20 amino acids,at least 20-30 amino acids, or at least 30-50 amino acids, or which isotherwise identifiable to one of ordinary skill in the art as having itsorigin in the starting sequence.

In another embodiment, a VH region of a binding molecule of theinvention shares an amino acid sequence identity that is about 80%, 85%,86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, tothat of a 9B11 VH region wherein the portion consists of at least 3-5amino acids, of at least 5-10 amino acids, at least 10-20 amino acids,at least 20-30 amino acids, or at least 30-50 amino acids, or which isotherwise identifiable to one of ordinary skill in the art as having itsorigin in the starting sequence.

In another embodiment, a CDR of a binding molecule of the inventionshares an amino acid sequence identity that is about 80%, 85%, 86%, 87%,88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, to that of a9B11 CDR, or which is otherwise identifiable to one of ordinary skill inthe art as having its origin in the starting sequence.

In another embodiment, the polypeptide or amino acid sequence which isderived from a particular starting polypeptide or amino acid sequenceshares an amino acid sequence identity that is about 80%, 85%, 86%, 87%,88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or which isotherwise identifiable to one of ordinary skill in the art as having itsorigin in the starting sequence.

An isolated nucleic acid molecule encoding a non-natural variant of apolypeptide can be created by introducing one or more nucleotidesubstitutions, additions or deletions into the nucleotide sequence ofthe binding molecule such that one or more amino acid substitutions,additions or deletions are introduced into the encoded protein.Mutations may be introduced by standard techniques, such assite-directed mutagenesis and PCR-mediated mutagenesis. In oneembodiment, conservative amino acid substitutions are made at one ormore non-essential amino acid residues. A “conservative amino acidsubstitution” is one in which the amino acid residue is replaced with anamino acid residue having a similar side chain. Families of amino acidresidues having similar side chains have been defined in the art,including basic side chains (e.g., lysine, arginine, histidine), acidicside chains (e.g., aspartic acid, glutamic acid), uncharged polar sidechains (e.g., glycine, asparagine, glutamine, serine, threonine,tyrosine, cysteine), nonpolar side chains (e.g., alanine, valine,leucine, isoleucine, proline, phenylalanine, methionine, tryptophan),beta-branched side chains (e.g., threonine, valine, isoleucine) andaromatic side chains (e.g., tyrosine, phenylalanine, tryptophan,histidine). Thus, a nonessential amino acid residue in a bindingmolecule polypeptide may be replaced with another amino acid residuefrom the same side chain family. In another embodiment, a string ofamino acids can be replaced with a structurally similar string thatdiffers in order and/or composition of side chain family members.

Alternatively, in another embodiment, mutations may be introducedrandomly along all or part of the binding molecule coding sequence.

Preferred binding molecules of the invention comprise framework andconstant region amino acid sequences derived from a human amino acidsequence. However, binding molecules may comprise framework and/orconstant region sequences derived from another mammalian species. Forexample, a primate framework region (e.g., non-human primate), heavychain portion, and/or hinge portion may be included in the subjectbinding molecules. In one embodiment, one or more murine amino acids maybe present in the framework region of a binding polypeptide, e.g., ahuman or non-human primate framework amino acid sequence may compriseone or more amino acid substitutions and/or backmutations in which thecorresponding murine amino acid residue is present. Preferred bindingmolecules of the invention are less immunogenic than the starting 9B11murine antibody.

The present invention also features chimeric and/or humanized bindingmolecules (i.e., chimeric and/or humanized immunoglobulins) specific forILT3. Chimeric and/or humanized binding molecules have the same orsimilar binding specificity and affinity as a mouse or other nonhumanbinding molecules that provide the starting material for construction ofa chimeric or humanized binding molecule.

A chimeric binding molecule is one whose light and heavy chain geneshave been constructed, typically by genetic engineering, fromimmunoglobulin gene segments belonging to different species. Forexample, the variable (V) segments of the genes from a mouse monoclonalbinding molecule may be joined to human o constant (C) segments, such asIgG1 or IgG4. Human isotype IgG1 is preferred. An exemplary chimericbinding molecule is thus a hybrid protein consisting of the V orantigen-binding domain from a mouse binding molecule and the C oreffector domain from a human binding molecule.

In one embodiment, the invention pertains to humanized variable regionsof the 9B11 binding molecule and polypeptides comprising such humanizedvariable regions. In one embodiment, a binding molecule of the inventioncomprises at least one humanized 9B11 binding molecule variable region,e.g., a light chain or heavy chain variable region.

The term “humanized binding molecule” refers to a binding moleculecomprising at least one chain comprising variable region frameworkresidues derived from a human binding molecule chain (referred to as theacceptor immunoglobulin or binding molecule) and at least onecomplementarity determining region derived from a mouse-bindingmolecule, (referred to as the donor immunoglobulin or binding molecule).Humanized binding molecules can be produced using recombinant DNAtechnology, which is discussed below. See for example, e.g., Hwang, W.Y. K., et al. (2005) Methods 36:35; Queen et al., Proc. Natl. Acad. Sci.USA, (1989), 86:10029-10033; Jones et al., Nature, (1986), 321:522-25;Riechmann et al., Nature, (1988), 332:323-27; Verhoeyen et al., Science,(1988), 239:1534-36; Orlandi et al., Proc. Natl. Acad. Sci. USA, (1989),86:3833-37; U.S. Pat. Nos. 5,225,539; 5,530,101; 5,585,089; 5,693,761;5,693,762; 6,180,370, Selick et al., WO 90/07861, and Winter, U.S. Pat.No. 5,225,539 (incorporated by reference in their entirety for allpurposes). The constant region(s), if present, are preferably is alsoderived from a human immunoglobulin.

When a preferred non-human donor binding molecule has been selected forhumanization, an appropriate human acceptor binding molecule may beobtained, e.g., from sequence databases of expressed human antibodygenes, from germline Ig sequences or a consensus sequence of severalhuman binding molecules.

In one embodiment, a CDR homology based method is used for humanization(see, e.g., Hwang, W. Y. K., et al. (2005) Methods 36:35, the contentsof which is incorporated in its entirety herein by this reference). Thismethod generally involves substitution of mouse CDRs into a humanvariable domain framework based on similarly structured mouse and humanCDRs rather than similarly structured mouse and human frameworks. Thesimilarity of the mouse and human CDRs is generally determined byidentifying human genes of the same chain type (light or heavy) thathave the same combination of canonical CDR structures as the mousebinding molecules and thus retain three-dimensional conformation of CDRpeptide backbones. Secondly, for each of the candidate variable geneswith matching canonical structures, residue to residue homology betweenthe mouse and candidate human CDRs is evaluated. Finally, to generate ahumanized binding molecule, CDR residues of the chosen human candidateCDR not already identical to the mouse CDR are converted to the mousesequence. In one embodiment, no mutations of the human framework areintroduced into the humanized binding molecule.

In one embodiment, human germline sequences are evaluated for CDRhomology to the ILT3 binding molecule CDRs. For example, for the murine9B11 antibody, all germ line light chain kappa chain V genes with a2-1-1 canonical structure in the IMGT database were compared with the9B11 antibody sequence. The same was done for the heavy chain where all1-3 germ line heavy chain V genes were compared to the 9B11 amino acidsequence. Accordingly, in one embodiment, a binding molecule of theinvention comprises a human kappa chain V region framework with a 2-1-1canonical structure. In another embodiment, a binding molecule of theinvention comprises a human heavy chain V region framework with a 1-3canonical structure.

The following potential human light chain germline sequences wereidentified and may provide framework regions for a binding molecule ofthe invention. More specifically, such molecules may provide a scaffoldin which any residue of the human light chain germline CDR not identicalto the 9B11 light chain CDR may be changed to the mouse CDR amino acid:

There are two alleles of the IGKV1-17 gene. The IMGT accession number ofallele *01 of the IGKV1-17 gene is X72808. The amino acid sequence is:

(SEQ ID NO: 36) DIQMTQSPSSLSASVGDRVTITCRASQGIRNDLGWYQQKPGKAPKRLIYAASSLQSGVPSRFSGSGSGTEFTLTISSLQPEDFATYYCLQHNSYP.

The IMGT accession number of allele *02 of the IGKV1-17 gene is D88255.The amino acid sequence is:

(SEQ ID NO: 37) DIQMTQSPSSLSASVGDRVTITCRASQGIRNDLGWYQQKPGKAPKRLIYAASSLQSGVPSRFSGSGSGTEFTLTISNLQPEDFATYYCLQHNSYP.

The IMGT accession number of the IGKV1-6 gene is M64858. The amino acidsequence is:

(SEQ ID NO: 38) AIQMTQSPSSLSASVGDRVTITCRASQGIRNDLGWYQQKPGKAPKLLIYAASSLQSGVPSRFSGSGSGTDFTLTISSLQPEDFATYYCLQDYNYP.

The IMGT accession number of the IGKV1-9 gene is Z00013. The amino acidsequence is:

(SEQ ID NO: 39) DIQLTQSPSFLSASVGDRVTITCRASQGISSYLAWYQQKPGKAPKLLIYAASTLQSGVPSRFSGSGSGTEFTLTISSLQPEDFATYYCQQLNSYP.

There are two alleles of the IGKV1-12 gene. The IMGT accession number ofallele *01 of the IGKV1-12 gene is V01577. The amino acid sequence is:

(SEQ ID NO: 40) DIQMTQSPSSVSASVGDRVTITCRASQGISSWLAWYQQKPGKAPKLLIYAASSLQSGVPSRFSGSGSGTDFTLTISSLQPEDFATYYCQQANSFP.

The IMGT accession number of allele *02 of the IGKV1-12 gene is V01576.The amino acid sequence is:

(SEQ ID NO: 41) DIQMTQSPSSVSASVGDRVTITCRASQGISSWLAWYQQKPGKAPKLLIYAASSLQSGVPSRFSGSGSGTDFTLTISSLQPEDFATYYCQQANSFP.

There are two alleles of the IGKV1D-16 gene. The IMGT accession numberof allele *01 of the IGKV1D-16 gene is K01323. The amino acid sequenceis:

(SEQ ID NO: 42) DIQMTQSPSSLSASVGDRVTITCRASQGISSWLAWYQQKPEKAPKSLIYAASSLQSGVPSRFSGSGSGTDFTLTISSLQPEDFATYYCQQYNSYP.

The IMGT accession number of allele *02 of the IGKV1D-16 gene is V00558.The amino acid sequence is:

(SEQ ID NO: 43) DIQMTQSPSSLSASVGDRVTITCRARQGISSWLAWYQQKPEKAPKSLIYAASSLQSGVPSRFSGSGSGTDFTLTISSLQPEDFATYYCQQYNSYP.

The IMGT accession number of the IGKV1-27 gene is X63398. The amino acidsequence is:

(SEQ ID NO: 44) DIQMTQSPSSLSASVGDRVTITCRASQGISNYLAWYQQKPGKVPKLLIYAASTLQSGVPSRFSGSGSGTDFTLTISSLQPEDVATYYCQKYNSAP.

There are two alleles of the IGKV1-39 gene. The IMGT accession number ofallele *01 of the IGKV1-39 gene is X59315. The amino acid sequence is:

(SEQ ID NO: 45) DIQMTQSPSSLSASVGDRVTITCRASQSISSYLNWYQQKPGKAPKLLIYAASSLQSGVPSRFSGSGSGTDFTLTISSLQPEDFATYYCQQSYSTP.

The IMGT accession number of allele *02 of the IGKV1-39 gene is X59318.The amino acid sequence is:

(SEQ ID NO: 46) DIQMTQSPSFLSASVGDRVTITCRASQSISSYLNWYQQKPGKAPKLLIYAASSLQSGVPSRFSGSGSGTDFTLTISSLQPEDFATYYCQCGYSTP.

The IMGT accession number of the IGKV1D-43 gene is X72817. The aminoacid sequence is:

(SEQ ID NO: 47) AIRMTQSPFSLSASVGDRVTITCWASQGISSYLAWYQQKPAKAPKLFIYYASSLQSGVPSRFSGSGSGTDYTLTISSLQPEDFATYYCQQYYSTP.

The following potential human heavy chain germline sequences wereidentified and may provide framework regions for a binding molecule ofthe invention. More specifically, such molecules may provide a scaffoldin which any residue of the human light chain germline CDR not identicalto the 9B11 light chain CDR may be changed to the mouse CDR amino acid:

There are two alleles of the IGHV3-21 gene. The IMGT accession number ofallele *01 of the IGHV3-21 gene is AB019439. The amino acid sequence is:

(SEQ ID NO: 48) EVQLVESGGGLVKPGGSLRLSCAASGFTFSSYSMNWVRQAPGKGLEWVSSISSSSSYIYYADSVKGRFTISRDNAKNSLYLQMNSLRAEDTAVYYCAR.

The IMGT accession number of allele *02 of the IGHV3-21 gene is M99658.The amino acid sequence is:

(SEQ ID NO: 49) EVQLVESGGGLVKPGGSLRLSCAASGFTFSSYSMNWVRQAPGKGLEWVSSISSSSSYIYYADSVKGRFTISRDNAKNSLYLQMNSLRAEDTAVYYCAR.

There are two alleles and a pseudogene of the IGHV3-11 gene. The IMGTaccession number of allele *01 of the IGHV3-11 gene is M99652. The aminoacid sequence is:

(SEQ ID NO: 50) QVQLVESGGGLVKPGGSLRLSCAASGFTFSDYYMSWIRQAPGKGLEWVSYISSSGSTIYYADSVKGRFTISRDNAKNSLYLQMNSLRAEDTAVYYCAR.

The IMGT accession number of allele *03 of the IGHV3-11 gene is X92287.The amino acid sequence is:

(SEQ ID NO: 51) QVQLLESGGGLVKPGGSLRLSCAASGFTFSDYYMSWIRQAPGKGLEWVSYISSSSSYTNYADSVKGRFTISRDNAKNSLYLQMNSLRAEDTAVYYCAR.

There are three alleles of the IGHV3-23 gene. The IMGT accession numberof allele *01 of the IGHV3-23 gene is M99660. The amino acid sequenceis:

(SEQ ID NO: 52) EVQLLESGGGLVQPGGSLRLSCAASGFTFSSYAMSWVRQAPGKGLEWVSAISGSGGSTYYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCAK.

The IMGT accession number of allele *02 of the IGHV3-23 gene is J00236.The amino acid sequence is:

(SEQ ID NO: 53) EVQLLESGGGLVQPGGSLRLSCAASGFTFSSYAMSWVRQAPGKGLEWVSAISGSGGSTYYGDSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCAK.

The IMGT accession number of allele *03 of the IGHV3-23 gene is U29481.The amino acid sequence is:

(SEQ ID NO: 54) EVQLLESGGGLVQPGGSLRLSCAASGFTFSSYAMSWVRQAPGKGLEWVSVIYSGGSSTYYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCAK.

There are three alleles of the IGHV3-48 gene. The IMGT accession numberof allele *01 of the IGHV3-48 gene is M99675. The amino acid sequenceis:

(SEQ ID NO: 55) EVQLVESGGGLVQPGGSLRLSCAASGFTFSSYSMNWVRQAPGKGLEWVSYISSSSSTIYYADSVKGRFTISRDNAKNSLYLQMNSLRAEDTAVYYCAR.

The IMGT accession number of allele *02 of the IGHV3-48 gene isAB019438. The amino acid sequence is:

(SEQ ID NO: 56) EVQLVESGGGLVQPGGSLRLSCAASGFTFSSYSMNWVRQAPGKGLEWVSYISSSSSTIYYADSVKGRFTISRDNAKNSLYLQMNSLRDEDTAVYYCAR.

The IMGT accession number of allele *03 of the IGHV3-48 gene is Z12358.The amino acid sequence is:

(SEQ ID NO: 57) EVQLVESGGGLVQPGGSLRLSCAASGFTFSSYEMNWVRQAPGKGLEWVSYISSSGSTIYYADSVKGRFTISRDNAKNSLYLQMNSLRAEDTAVYYCAR.

There are five alleles of the IGHV3-64 gene. The IMGT accession numberof allele *01 of the IGHV3-64 gene is M99682. The amino acid sequenceis:

(SEQ ID NO: 58) EVQLVESGGGLVQPGGSLRLSCAASGFTFSSYAMHWVRQAPGKGLEYVSAISSNGGSTYYANSVKGRFTISRDNSKNTLYLQMGSLRAEDMAVYYCAR.

The IMGT accession number of allele *02 of the IGHV3-64 gene isAB019437. The amino acid sequence is:

(SEQ ID NO: 59) EVQLVESGEGLVQPGGSLRLSCAASGFTFSSYAMHWVRQAPGKGLEYVSAISSNGGSTYYADSVKGRFTISRDNSKNTLYLQMGSLRAEDMAVYYCAR.

The IMGT accession number of allele *03 of the IGHV3-64 gene is M77298.The amino acid sequence is:

(SEQ ID NO: 60) EVQLVESGGGLVQPGGSLRLSCSASGFTFSSYAMHWVRQAPGKGLEYVSAISSNGGSTYYADSVKGRFTISRDNSKNTLYVQMSSLRAEDTAVYYCVK.

The IMGT accession number of allele *04 of the IGHV3-64 gene is M77299.The amino acid sequence is:

(SEQ ID NO: 61) QVQLVESGGGLVQPGGSLRLSCSASGFTFSSYAMHWVRQAPGKGLEYVSAISSNGGSTYYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCAR.

The IMGT accession number of allele *05 of the IGHV3-64 gene is M77301.The amino acid sequence is:

(SEQ ID NO: 62) EVQLVESGGGLVQPGGSLRLSCSASGFTFSSYAMHWVRQAPGKGLEYVSAISSNGGSTYYADSVKGRFTISRDNSKNTLYVQMSSLRAEDTAVYYCVK.

Each of these germline sequences may be used to provide frameworkregions for use with one or more 9B11 CDRs.

As used herein, “canonical structures” are conserved hypervariable loopconformations made by different CDRs by which the binding molecule formsthe antigen contacts. The assignment of canonical structure classes to anew binding molecule can be achieved using publicly available software.

In another embodiment, the substitution of mouse CDRs into a humanvariable domain framework is based on the retention of the correctspatial orientation of the mouse variable domain framework byidentifying human variable domain frameworks which will retain the sameconformation as the mouse variable domain frameworks from which the CDRswere derived. In one embodiment, this is achieved by obtaining the humanvariable domains from human binding molecules whose framework sequencesexhibit a high degree of sequence identity with the murine variableframework domains from which the CDRs were derived. See Kettleborough etal., Protein Engineering 4:773 (1991); Kolbinger et al., ProteinEngineering 6:971 (1993) and Carter et al., WO 92/22653.

Preferably the human acceptor binding molecule retains the canonical andinterface residues of the donor binding molecule. Additionally, thehuman acceptor binding molecule preferably has substantial similarity inthe length of CDR loops. See Kettleborough et al., Protein Engineering4:773 (1991); Kolbinger et al., Protein Engineering 6:971 (1993) andCarter et al., WO 92/22653.

In another embodiment, appropriate human acceptor sequences may beselected based on homology to framework regions of the 9B11 bindingmolecule. For example, the amino acid sequence of the 9B11 bindingmolecule may be compared to the amino acid sequence of other knownbinding molecules by, for example, by comparing the FR regions or the,variable region sequences of the 9B11 amino acid sequence against apublicly available database of known binding molecules and selectingthose sequences with the highest percent identity of amino acids in thevariable or FR region, i.e., 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%,92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%. In one embodiment, theframework sequence set forth in SEQ ID NO:63 may be used(EVQLVESGGGLVKPGGSLRLSCAASGFAFSSYDMSWVRQAPGKGLEWVSTISSSGSYTYYPDSVKGRFTISRDNAKNSLYLQMNSLRAEDTAVYYCARL WGAMDYWGQGTLVTVSS(SEQ ID NO:63; (Framework residues are in bold))). In anotherembodiment, the framework sequence set forth in SEQ ID NO:64 may be used(DIQMTQSPSSLSASVGDRVTITCRASQGLTNDLHWYQQKPGKAPKRLIYYASQSISGVPSRFSGSGSGTEFTLTISSLQPEDFATYYCQQSNSWPFTFGQGT KLEIKR (SEQ IDNO:64; Framework residues are in bold))).

Having identified the complementarity determining regions of the murinedonor immunoglobulin and appropriate human acceptor immunoglobulins, thenext step is to determine which, if any, residues from these componentsshould be substituted to optimize the properties of the resultinghumanized binding molecule. In general, substitution of human amino acidresidues with murine should be minimized, because introduction of murineresidues increases the risk of the binding molecule eliciting ahuman-anti-mouse-antibody (HAMA) response in humans. Art-recognizedmethods of determining immune response can be performed to monitor aHAMA response in a particular patient or during clinical trials.Patients administered humanized binding molecules can be given animmunogenicity assessment at the beginning and throughout theadministration of said therapy. The HAMA response is measured, forexample, by detecting antibodies to the humanized therapeutic reagent,in serum samples from the patient using a method known to one in theart, including surface plasmon resonance technology (BIACORE) and/orsolid-phase ELISA analysis.

When necessary, one or more residues in the human framework regions canbe changed or substituted to residues at the corresponding positions inthe murine antibody so as to preserve the binding affinity of thehumanized antibody to the antigen. This change is sometimes called“backmutation”. Certain amino acids from the human variable regionframework residues are selected for back mutation based on theirpossible influence on CDR conformation and/or binding to antigen. Theplacement of murine CDR regions with human variable framework region canresult in conformational restraints, which, unless corrected bysubstitution of certain amino acid residues, lead to loss of bindingaffinity.

In one embodiment, the selection of amino acid residues for backmutationcan be determined, in part, by computer modeling, using art recognizedtechniques. In general, molecular models are produced starting fromsolved structures for immunoglobulin chains or domains thereof. Thechains to be modeled are compared for amino acid sequence similaritywith chains or domains of solved three-dimensional structures, and thechains or domains showing the greatest sequence similarity is/areselected as starting points for construction of the molecular model.Chains or domains sharing at least 50% sequence identity are selectedfor modeling, and preferably those sharing at least 60%, 70%, 80%, 90%sequence identity or more are selected for modeling. The solved startingstructures are modified to allow for differences between the actualamino acids in the immunoglobulin chains or domains being modeled, andthose in the starting structure. The modified structures are thenassembled into a composite immunoglobulin. Finally, the model is refinedby energy minimization and by verifying that all atoms are withinappropriate distances from one another and that bond lengths and anglesare within chemically acceptable limits.

The selection of amino acid residues for substitution can also bedetermined, in part, by examination of the characteristics of the aminoacids at particular locations, or empirical observation of the effectsof substitution or mutagenesis of particular amino acids. For example,when an amino acid differs between a murine variable region frameworkresidue and a selected human variable region framework residue, thehuman framework amino acid may be substituted by the equivalentframework amino acid from the mouse binding molecule when it isreasonably expected that the amino acid: (1) noncovalently binds antigendirectly, (2) is adjacent to a CDR region, (3) otherwise interacts witha CDR region (e.g., is within about 3-6 Å of a CDR region as determinedby computer modeling), or (4) participates in the VL-VH interface.

Residues which “noncovalently bind antigen directly” include amino acidsin positions in framework regions which are have a good probability ofdirectly interacting with amino acids on the antigen according toestablished chemical forces, for example, by hydrogen bonding, Van derWaals forces, hydrophobic interactions, and the like.

Residues which are “adjacent to a CDR region” include amino acidresidues in positions immediately adjacent to one or more of the CDRs inthe primary sequence of the humanized immunoglobulin chain, for example,in positions immediately adjacent to a CDR as defined by Kabat, or a CDRas defined by Chothia (See e.g., Chothia and Lesk JMB 196:901 (1987)).These amino acids are particularly likely to interact with the aminoacids in the CDRs and, if chosen from the acceptor, may distort thedonor CDRs and reduce affinity. Moreover, the adjacent amino acids mayinteract directly with the antigen (Amit et al., Science, 233:747(1986), which is incorporated herein by reference) and selecting theseamino acids from the donor may be desirable to keep all the antigencontacts that provide affinity in the original binding molecule.

Residues that “otherwise interact with a CDR region” include those thatare determined by secondary structural analysis to be in a spatialorientation sufficient to effect a CDR region. In one embodiment,residues that “otherwise interact with a CDR region” are identified byanalyzing a three-dimensional model of the donor immunoglobulin (e.g., acomputer-generated model). A three-dimensional model, typically of theoriginal donor binding molecule, shows that certain amino acids outsideof the CDRs are close to the CDRs and have a good probability ofinteracting with amino acids in the CDRs by hydrogen bonding, Van derWaals forces, hydrophobic interactions, etc. At those amino acidpositions, the donor immunoglobulin amino acid rather than the acceptorimmunoglobulin amino acid may be selected. Amino acids according to thiscriterion will generally have a side chain atom within about 3 Å of someatom in the CDRs and must contain an atom that could interact with theCDR atoms according to established chemical forces, such as those listedabove.

In the case of atoms that may form a hydrogen bond, the 3 Å is measuredbetween their nuclei, but for atoms that do not form a bond, the 3 Å ismeasured between their Van der Waals surfaces. Hence, in the lattercase, the nuclei must be within about 6 Å (3 Å plus the sum of the Vander Waals radii) for the atoms to be considered capable of interacting.In many cases the nuclei will be from 4 or 5 to 6 Å apart. Indetermining whether an amino acid can interact with the CDRs, it ispreferred not to consider the last 8 amino acids of heavy chain CDR aspart of the CDRs, because from the viewpoint of structure, these 8 aminoacids behave more as part of the framework.

Amino acids that are capable of interacting with amino acids in theCDRs, may be identified in yet another way. The solvent accessiblesurface area of each framework amino acid is calculated in two ways: (1)in the intact binding molecule, and (2) in a hypothetical moleculeconsisting of the binding molecule with its CDRs removed. A significantdifference between these numbers of about 10 square angstroms or moreshows that access of the framework amino acid to solvent is at leastpartly blocked by the CDRs, and therefore that the amino acid is makingcontact with the CDRs. Solvent accessible surface area of an amino acidmay be calculated based on a three-dimensional model of an bindingmolecule, using algorithms known in the art (e.g., Connolly, J. Appl.Cryst. 16:548 (1983) and Lee and Richards, J. Mol. Biol. 55:379 (1971),both of which are incorporated herein by reference). Framework aminoacids may also occasionally interact with the CDRs indirectly, byaffecting the conformation of another framework amino acid that in turncontacts the CDRs.

The amino acids at several positions in the framework are known to becapable of interacting with the CDRs in many binding molecules (Chothiaand Lesk, supra, Chothia et al., supra and Tramontano et al., J. Mol.Biol. 215:175 (1990), all of which are incorporated herein byreference). Notably, the amino acids at positions 2, 48, 64 and 71 ofthe light chain and 26-30, 71 and 94 of the heavy chain (numberingaccording to Kabat) are known to be capable of interacting with the CDRsin many binding molecules. The amino acids at positions 35 in the lightchain and 93 and 103 in the heavy chain are also likely to interact withthe CDRs. At all these numbered positions, choice of the donor aminoacid rather than the acceptor amino acid (when they differ) to be in thehumanized immunoglobulin is preferred. On the other hand, certainresidues capable of interacting with the CDR region, such as the first 5amino acids of the light chain, may sometimes be chosen from theacceptor immunoglobulin without loss of affinity in the humanizedbinding molecule.

Residues which “participate in the VL-VH interface” or “packingresidues” include those residues at the interface between VL and VH asdefined, for example, by Novotny and Haber (Proc. Natl. Acad Sci. USA,82:4592-66 (1985)) or Chothia et al, supra. Generally, unusual packingresidues should be retained in the humanized binding molecule if theydiffer from those in the human frameworks.

In general, one or more of the amino acids fulfilling the above criteriais substituted. In some embodiments, all or most of the amino acidsfulfilling the above criteria are substituted. Occasionally, there issome ambiguity about whether a particular amino acid meets the abovecriteria, and alternative variant binding molecules are produced, one ofwhich has that particular substitution, the other of which does not.Alternative variant binding molecules so produced can be tested in anyof the assays described herein for the desired activity, and thepreferred binding molecule selected.

Usually the CDR regions in humanized binding molecules are substantiallyidentical, and more usually, identical to the corresponding CDR regionsof the donor binding molecule. Although not usually desirable, it issometimes possible to make one or more conservative amino acidsubstitutions of CDR residues without appreciably affecting the bindingaffinity of the resulting humanized binding molecule. By conservativesubstitutions it is meant combinations such as Gly, Ala; Val, Ile, Leu;Asp, Glu; Asn, Gln; Ser, Thr; Lys, Arg; and Phe, Tyr.

Additional candidates for substitution are acceptor human frameworkamino acids that are unusual or “rare” for a human immunoglobulin atthat position. These amino acids can be substituted with amino acidsfrom the equivalent position of the mouse donor binding molecule or fromthe equivalent positions of more typical human immunoglobulins. Forexample, substitution may be desirable when the amino acid in a humanframework region of the acceptor immunoglobulin is rare for thatposition and the corresponding amino acid in the donor immunoglobulin iscommon for that position in human immunoglobulin sequences; or when theamino acid in the acceptor immunoglobulin is rare for that position andthe corresponding amino acid in the donor immunoglobulin is also rare,relative to other human sequences. These criterion help ensure that anatypical amino acid in the human framework does not disrupt the bindingmolecule structure. Moreover, by replacing an unusual human acceptoramino acid with an amino acid from the donor binding molecule thathappens to be typical for human binding molecules, the humanized bindingmolecule may be made less immunogenic.

The term “rare”, as used herein, indicates an amino acid occurring atthat position in less than about 20% but usually less than about 10% ofsequences in a representative sample of sequences, and the term“common”, as used herein, indicates an amino acid occurring in more thanabout 25% but usually more than about 50% of sequences in arepresentative sample. For example, all human light and heavy chainvariable region sequences are respectively grouped into “subgroups” ofsequences that are especially homologous to each other and have the sameamino acids at certain critical positions (Kabat et al., supra). Whendeciding whether an amino acid in a human acceptor sequence is “rare” or“common” among human sequences, it will often be preferable to consideronly those human sequences in the same subgroup as the acceptorsequence.

Additional candidates for substitution are acceptor human frameworkamino acids that would be identified as part of a CDR region under thealternative definition proposed by Chothia et al., supra. Additionalcandidates for substitution are acceptor human framework amino acidsthat would be identified as part of a CDR region under the AbM and/orcontact definitions. Notably, CDR1 in the variable heavy chain isdefined as including residues 26-32.

Additional candidates for substitution are acceptor framework residuesthat correspond to a rare or unusual donor framework residue. Rare orunusual donor framework residues are those that are rare or unusual (asdefined herein) for murine binding molecules at that position. Formurine binding molecules, the subgroup can be determined according toKabat and residue positions identified which differ from the consensus.These donor specific differences may point to somatic mutations in themurine sequence which enhances activity. Unusual residues that arepredicted to affect binding are retained, whereas residues predicted tobe unimportant for binding can be substituted.

Additional candidates for substitution are non-germline residuesoccurring in an acceptor framework region. For example, when an acceptorbinding molecule chain (i.e., a human binding molecule chain sharingsignificant sequence identity with the donor binding molecule chain) isaligned to a germline binding molecule chain (likewise sharingsignificant sequence identity with the donor chain), residues notmatching between acceptor chain framework and the germline chainframework can be substituted with corresponding residues from thegermline sequence.

Other than the specific amino acid substitutions discussed above, theframework regions of humanized binding molecules are usuallysubstantially identical, and more usually, identical to the frameworkregions of the human binding molecules from which they were derived. Ofcourse, many of the amino acids in the framework region make little orno direct contribution to the specificity or affinity of a bindingmolecule. Thus, many individual conservative substitutions of frameworkresidues can be tolerated without appreciable change of the specificityor affinity of the resulting humanized binding molecule. Thus, in oneembodiment the variable framework region of the humanized bindingmolecule shares at least 85% sequence identity to a human variableframework region sequence or consensus of such sequences. In anotherembodiment, the variable framework region of the humanized bindingmolecule shares at least 90%, preferably 95%, more preferably 96%, 97%,98% or 99% sequence identity to a human variable framework regionsequence or consensus of such sequences. In general, however, suchsubstitutions are undesirable.

In one embodiment, a binding molecule of the invention further comprisesat least one backmutation of a human amino acid residue to thecorresponding mouse amino acid residue where the amino acid residue isan interface packing residue. “Interface packing residues” include thoseresidues at the interface between VL and VH as defined, for example, byNovotny and Haber, Proc. Natl. Acad. Sci. USA, 82:4592-66 (1985).

In one embodiment, a binding molecule of the invention further comprisesat least one backmutation of a human amino acid residue to thecorresponding mouse amino acid residue is a canonical residue.“Canonical residues” are conserved framework residues within a canonicalor structural class known to be important for CDR conformation(Tramontano et al., J. Mol. Biol. 215:175 (1990), all of which areincorporated herein by reference). Canonical residues include 2, 25,27B, 28, 29, 30, 33, 48, 51, 52, 64, 71, 90, 94 and 95 of the lightchain and residues 24, 26, 27 29, 34, 54, 55, 71 and 94 of the heavychain. Additional residues (e.g., CDR structure-determining residues)can be identified according to the methodology of Martin and Thorton(1996) J. Mol. Biol. 263:800.

In one embodiment, a binding molecule of the invention further comprisesat least one backmutation of a human amino acid residue to thecorresponding mouse amino acid residue where the amino acid residue isat a position capable of interacting with a CDR. Notably, the aminoacids at positions 2, 48, 64 and 71 of the light chain and 26-30, 71 and94 of the heavy chain (numbering according to Kabat) are known to becapable of interacting with the CDRs in many antibodies. The amino acidsat positions 35 in the light chain and 93 and 103 in the heavy chain arealso likely to interact with the CDRs.

Based on CLUSTAL W analysis, several amino acid residues in the humanframework were identified for potential substitution, e.g., withcorresponding amino acid residues from the 9B11 light chain. Theseincluded positions 3, 4, 9, 10, 13, 14, 15, 18, 20, 21, 22, 41, 42, 43,45, 46, 49, 58, 70, 76, 78, 79, 80, 84, 85, 86, 87, and 100.

In one embodiment, a variable light chain framework of a bindingmolecule of the invention further comprises at least one substitution ofa human amino acid residue to the corresponding mouse amino acid residueselected from the group consisting of: Q3V, (i.e., the Q at position 1of the CDR-grafted antibody which comprises murine CDRs and human FRregions is mutated to a V, which is the corresponding amino acid residuein the 9B11 antibody (without leader)), Q3L, Q31, M4L, M4V, M4I, S9A,S9G, S9V, S9L, S9I, S10T, S10Y, A13V, A13L, A13I, S14T, S14Y, VP15,R18S, R18T, R18Y, T20S, T20Y, I21L, I21V, T22S, T22Y, G41H, G41C, K42E,K42D, A43S, A43T, A43Y, K45R, R46L, R46I, R46V, Y49K, Y49R, V58I, V58L,E70D, S76N, S76Q, L78V, L78I, Q79E, Q79D, P80T, P80S, P80Y, A84G, A84A,T85L, T85I, Y86F, Y86W, Y86V, Y86L, Y86I, Y87F, Y87W, Y87V, Y87L, Y87I,Q100A, Q100P, and Q100G.

Based on CLUSTAL W analysis, several amino acid residues in the humanframework were identified for potential substitution, e.g., withcorresponding amino acid residues from the 9B11 heavy chain. Theseincluded positions 3, 10, 19, 40, 42, 44, 49, 76, 78, 84, 88, 93, and97.

In one embodiment, a variable heavy chain framework of a bindingmolecule of the invention further comprises at least one substitution ofa human amino acid residue to the corresponding mouse amino acid residueselected from the group consisting of: Q3K (i.e., the Q at position 3 ofthe CDR-grafted antibody which comprises murine CDRs and human FRregions is mutated to a K, which is the corresponding amino acid residuein the 9B11 antibody), Q3H, Q3R, G10D, G10E, R19K, R19H, A40T, A40Y,A40S, G42E, G42D, G44R, G44K, S49A, S49G, S49V, S49L, S49I, K76R, K76H,S78T, S78Y, N84S, N84T, N84Y, A88S, A88T, A88Y, V93L, V93I, V93A, V93G,A97E, and A97D.

The humanized binding molecules preferably exhibit a specific bindingaffinity for antigen of at least 10⁷, 10⁸, 10⁹ or 10¹⁰ M⁻¹. Usually theupper limit of binding affinity of the humanized binding molecules forantigen is within a factor of three, four or five of that of the donorimmunoglobulin. Often the lower limit of binding affinity is also withina factor of three, four or five of that of donor immunoglobulin.Alternatively, the binding affinity can be compared to that of ahumanized binding molecule having no substitutions (e.g., a bindingmolecule having donor CDRs and acceptor FRs, but no FR substitutions).In such instances, the binding of the optimized binding molecule (withsubstitutions) is preferably at least two- to three-fold greater, orthree- to four-fold greater, than that of the unsubstituted bindingmolecule. For making comparisons, activity of the various bindingmolecules can be determined, for example, by BIACORE (i.e., surfaceplasmon resonance using unlabelled reagents) or competitive bindingassays.

Having conceptually selected the CDR and framework components ofhumanized binding molecules, a variety of methods are available forproducing such binding molecules. Because of the degeneracy of the code,a variety of nucleic acid sequences will encode each binding moleculeamino acid sequence. The desired nucleic acid sequences can be producedby de novo solid-phase DNA synthesis or by PCR mutagenesis of an earlierprepared variant of the desired polynucleotide.

Oligonucleotide-mediated mutagenesis is a preferred method for preparingsubstitution, deletion and insertion variants of target polypeptide DNA.See Adelman et al. (DNA 2:183 (1983)). Briefly, the target polypeptideDNA is altered by hybridizing an oligonucleotide encoding the desiredmutation to a single-stranded DNA template. After hybridization, a DNApolymerase is used to synthesize an entire second complementary strandof the template that incorporates the oligonucleotide primer, andencodes the selected alteration in the target polypeptide DNA.

The variable segments of binding molecules produced as described supra(e.g., the heavy and light chain variable regions of chimeric,humanized, or human binding molecules) are typically linked to at leasta portion of an immunoglobulin constant region (Fc), typically that of ahuman immunoglobulin. Human constant region DNA sequences can beisolated in accordance with well known procedures from a variety ofhuman cells, but preferably immortalized B cells (see Kabat et al.,supra, and Liu et al., W087/02671) (each of which is incorporated byreference in its entirety for all purposes). Ordinarily, the bindingmolecule will contain both light chain and heavy chain constant regions.The heavy chain constant region usually includes CH1, hinge, CH2, CH3,and CH4 regions. A binding molecule described herein include antibodieshaving all types of constant regions, including IgM, IgG, IgD, IgA andIgE, and any isotype, including IgG1, IgG2, IgG3 and IgG4. The choice ofconstant region depends, in part, or whether binding molecule-dependentcomplement and/or cellular mediated toxicity is desired. For example,isotopes IgG1 and IgG3 have complement activity and isotypes IgG2 andIgG4 do not. When it is desired that the binding molecule (e.g.,humanized binding molecule) exhibit cytotoxic activity, the constantdomain is usually a complement fixing constant domain and the class istypically IgG1. When such cytotoxic activity is not desirable, theconstant domain may be, e.g., of the IgG2 class. Choice of isotype canalso affect passage of antibody into the brain. Human isotype IgG1 ispreferred. Light chain constant regions can be lambda or kappa. Thehumanized binding molecule may comprise sequences from more than oneclass or isotype. Binding molecules can be expressed as tetramerscontaining two light and two heavy chains, as separate heavy chains,light chains, as Fab, Fab′ F(ab′)2, and Fv, or as single chain bindingmolecules in which heavy and light chain variable domains are linkedthrough a spacer.

III. Production of Binding Molecules

The present invention features binding molecules having specificity forILT3, e.g., human ILT3. Such binding molecules can be used informulating various therapeutic compositions of the invention or,preferably, provide complementarity determining regions for theproduction of humanized or chimeric binding molecules (described indetail below). The production of non-human monoclonal binding molecules,e.g., murine, guinea pig, primate, rabbit or rat, can be accomplishedby, for example, immunizing the animal with ILT3 or with a nucleic acidmolecule encoding ILT3. For example, the 9B11 binding molecule was madeby placing the gene encoding human ILT3 in an expression vector andimmunizing animals. A longer polypeptide comprising ILT3 or animmunogenic fragment of ILT3 or anti-idiotypic binding molecule of ILT3can also be used. (see, for example, Harlow & Lane, supra, incorporatedby reference for all purposes). Such an immunogen can be obtained from anatural source, by peptide synthesis or by recombinant expression.Optionally, the immunogen can be administered, fused or otherwisecomplexed with a carrier protein, as described below. Optionally, theimmunogen can be administered with an adjuvant. The term “adjuvant”refers to a compound that when administered in conjunction with anantigen augments the immune response to the antigen, but whenadministered alone does not generate an immune response to the antigen.Adjuvants can augment an immune response by several mechanisms includinglymphocyte recruitment, stimulation of B and/or T cells, and stimulationof macrophages. Several types of adjuvants can be used as describedbelow. Complete Freund's adjuvant followed by incomplete adjuvant ispreferred for immunization of laboratory animals.

Rabbits or guinea pigs are typically used for making polyclonal bindingmolecules. Exemplary preparation of polyclonal binding molecules, e.g.,for passive protection, can be performed as follows. Animals areimmunized with 100 μg ILT3, plus adjuvant, and euthanized at 4-5 months.Blood is collected and IgG is separated from other blood components.Binding molecules specific for the immunogen may be partially purifiedby affinity chromatography. An average of about 0.5-1.0 mg ofimmunogen-specific binding molecule is obtained per animal, giving atotal of 60-120 mg.

Mice are typically used for making monoclonal binding molecules.Monoclonals can be prepared against a fragment by injecting the fragmentor longer form of ILT3 into a mouse, preparing hybridomas and screeningthe hybridomas for a binding molecule that specifically binds to ILT3.Optionally, binding molecules are screened for binding to a specificregion or desired fragment of ILT3 without binding to othernonoverlapping fragments of ILT3. The latter screening can beaccomplished by determining binding of a binding molecule to acollection of deletion mutants of a ILT3 peptide and determining whichdeletion mutants bind to the binding molecule. Binding can be assessed,for example, by Western blot or ELISA. The smallest fragment to showspecific binding to the binding molecule defines the epitope of thebinding molecule. Alternatively, epitope specificity can be determinedby a competition assay in which a test and reference binding moleculecompete for binding to ILT3. If the test and reference binding moleculecompete, then they bind to the same epitope (or epitopes sufficientlyproximal) such that binding of one binding molecule interferes withbinding of the other. The preferred isotype for such binding moleculesis mouse isotype IgG2a or equivalent isotype in other species. Mouseisotype IgG2a is the equivalent of human isotype IgG1.

In another embodiment, DNA encoding a binding molecule may be readilyisolated and sequenced using conventional procedures (e.g., by usingoligonucleotide probes that are capable of binding specifically to genesencoding the heavy and light chains of murine binding molecules). Theisolated and subcloned hybridoma cells serve as a preferred source ofsuch DNA. Once isolated, the DNA may be placed into expression vectors,which are then transfected into prokaryotic or eukaryotic host cellssuch as E. coli cells, simian COS cells, Chinese Hamster Ovary (CHO)cells or myeloma cells that do not otherwise produce immunoglobulins.More particularly, the isolated DNA (which may be synthetic as describedherein) may be used to clone constant and variable region sequences forthe manufacture of binding molecules as described in Newman et al., U.S.Pat. No. 5,658,570, filed Jan. 25, 1995, which is incorporated byreference herein. Essentially, this entails extraction of RNA from theselected cells, conversion to cDNA, and amplification by PCR using Igspecific primers. Suitable primers for this purpose are also describedin U.S. Pat. No. 5,658,570. Transformed cells expressing the desiredantibody may be produced in relatively large quantities to provideclinical and commercial supplies of the binding molecule.

Those skilled in the art will also appreciate that DNA encoding bindingmolecules or fragments thereof (e.g., antigen binding sites) may also bederived from antibody phage libraries, e.g., using pd phage or Fdphagemid technology. Exemplary methods are set forth, for example, in EP368 684 B1; U.S. Pat. No. 5,969,108, Hoogenboom, H. R. and Chames. 2000.Immunol. Today 21:371; Nagy et al. 2002. Nat. Med. 8:801; Huie et al.2001. Proc. Natl. Acad Sci. USA 98:2682; Lui et al. 2002 J. Mol. Biol.315:1063, each of which is incorporated herein by reference. Severalpublications (e.g., Marks et al. Bio/Technology 10:779-783 (1992)) havedescribed the production of high affinity human binding molecules bychain shuffling, as well as combinatorial infection and in vivorecombination as a strategy for constructing large phage libraries. Inanother embodiment, Ribosomal display can be used to replacebacteriophage as the display platform (see, e.g., Hanes et al. 2000.Nat. Biotechnol. 18:1287; Wilson et al. 2001. Proc. Natl. Acad. Sci. USA98:3750; or Irving et al. 2001 J. Immunol. Methods 248:31. In yetanother embodiment, cell surface libraries can be screened for bindingmolecules (Boder et al. 2000. Proc. Natl. Acad. Sci. USA 97:10701;Daugherty et al. 2000 J. Immunol. Methods 243:211. Such proceduresprovide alternatives to traditional hybridoma techniques for theisolation and subsequent cloning of monoclonal binding molecules.

Yet other embodiments of the present invention comprise the generationof human or substantially human binding molecules in transgenic animals(e.g., mice) that are incapable of endogenous immunoglobulin production(see e.g., U.S. Pat. Nos. 6,075,181, 5,939,598, 5,591,669 and 5,589,369each of which is incorporated herein by reference). For example, it hasbeen described that the homozygous deletion of the antibody heavy-chainjoining region in chimeric and germ-line mutant mice results in completeinhibition of endogenous antibody production. Transfer of a humanimmunoglobulin gene array to such germ line mutant mice will result inthe production of human binding molecules upon antigen challenge.Another preferred means of generating human binding molecules using SCIDmice is disclosed in U.S. Pat. No. 5,811,524 which is incorporatedherein by reference. It will be appreciated that the genetic materialassociated with these human binding molecules may also be isolated andmanipulated as described herein.

Yet another highly efficient means for generating recombinant bindingmolecules is disclosed by Newman, Biotechnology, 10: 1455-1460 (1992).Specifically, this technique results in the generation of primatizedbinding molecules that contain monkey variable domains and humanconstant sequences. This reference is incorporated by reference in itsentirety herein. Moreover, this technique is also described in U.S. Pat.Nos. 5,658,570, 5,693,780 and 5,756,096 each of which is incorporatedherein by reference.

In another embodiment, lymphocytes can be selected by micromanipulationand the variable genes isolated. For example, peripheral bloodmononuclear cells can be isolated from an immunized mammal and culturedfor about 7 days in vitro. The cultures can be screened for specificIgGs that meet the screening criteria. Cells from positive wells can beisolated. Individual Ig-producing B cells can be isolated by FACS or byidentifying them in a complement-mediated hemolytic plaque assay.Ig-producing B cells can be micromanipulated into a tube and the VH andVL genes can be amplified using, e.g., RT-PCR. The VH and VL genes canbe cloned into an antibody expression vector and transfected into cells(e.g., eukaryotic or prokaryotic cells) for expression.

Moreover, genetic sequences useful for producing the polypeptides of thepresent invention may be obtained from a number of different sources.For example, as discussed extensively above, a variety of human antibodygenes are available in the form of publicly accessible deposits. Manysequences of antibodies and antibody-encoding genes have been publishedand suitable antibody genes can be chemically synthesized from thesesequences using art recognized techniques. Oligonucleotide synthesistechniques compatible with this aspect of the invention are well knownto the skilled artisan and may be carried out using any of severalcommercially available automated synthesizers. In addition, DNAsequences encoding several types of heavy and light chains set forthherein can be obtained through the services of commercial DNA synthesisvendors. The genetic material obtained using any of the foregoingmethods may then be altered or synthetic to provide obtain polypeptidesof the present invention.

Alternatively, antibody-producing cell lines may be selected andcultured using techniques well known to the skilled artisan. Suchtechniques are described in a variety of laboratory manuals and primarypublications. In this respect, techniques suitable for use in theinvention as described below are described in Current Protocols inImmunology, Coligan et al., Eds., Green Publishing Associates andWiley-Interscience, John Wiley and Sons, New York (1991) which is hereinincorporated by reference in its entirety, including supplements.

As is well known, RNA may be isolated from the original hybridoma cellsor from other transformed cells by standard techniques, such asguanidinium isothiocyanate extraction and precipitation followed bycentrifugation or chromatography. Where desirable, mRNA may be isolatedfrom total RNA by standard techniques such as chromatography on oligo dTcellulose. Suitable techniques are familiar in the art.

In one embodiment, cDNAs that encode the light and the heavy chains ofthe binding molecule may be made, either simultaneously or separately,using reverse transcriptase and DNA polymerase in accordance with wellknown methods. PCR may be initiated by consensus constant region primersor by more specific primers based on the published heavy and light chainDNA and amino acid sequences. As discussed above, PCR also may be usedto isolate DNA clones encoding the binding molecule light and heavychains. In this case the libraries may be screened by consensus primersor larger homologous probes, such as mouse constant region probes.

DNA, typically plasmid DNA, may be isolated from the cells usingtechniques known in the art, restriction mapped and sequenced inaccordance with standard, well known techniques set forth in detail,e.g., in the foregoing references relating to recombinant DNAtechniques. Of course, the DNA may be synthetic according to the presentinvention at any point during the isolation process or subsequentanalysis.

In one embodiment, a binding molecule of the invention comprises orconsists of an antigen binding fragment of an antibody. The term“antigen-binding fragment” refers to a polypeptide fragment of animmunoglobulin or antibody that binds antigen or competes with intactantibody (i.e., with the intact antibody from which they were derived)for antigen binding (i.e., specific binding). As used herein, the term“fragment” of an antibody molecule includes antigen-binding fragments ofantibodies, for example, an antibody light chain (VL), an antibody heavychain (VH), a single chain antibody (scFv), a F(ab′)2 fragment, a Fabfragment, an Fd fragment, an Fv fragment, and a single domain antibodyfragment (DAb). Fragments can be obtained, e.g., via chemical orenzymatic treatment of an intact or complete antibody or antibody chainor by recombinant means.

In one embodiment, a binding molecule of the invention is an engineeredor modified antibody. Engineered forms of antibodies include, forexample, minibodies, diabodies, diabodies fused to CH3 molecules,tetravalent antibodies, intradiabodies (e.g., Jendreyko et al. 2003. J.Biol. Chem. 278:47813), bispecific antibodies, fusion proteins (e.g.,antibody cytokine fusion proteins) or, bispecific antibodies. Otherimmunoglobulins (Ig) and certain variants thereof are described, forexample in U.S. Pat. No. 4,745,055; EP 256,654; Faulkner et al., Nature298:286 (1982); EP 120,694; EP 125,023; Morrison, J. Immun. 123:793(1979); Kohler et al., Proc. Natl. Acad. Sci. USA 77:2197 (1980); Rasoet al., Cancer Res. 41:2073 (1981); Morrison et al., Ann. Rev. Immunol.2:239 (1984); Morrison, Science 229:1202 (1985); Morrison et al., Proc.Natl. Acad. Sci. USA 81:6851 (1984); EP 255,694; EP 266,663; and WO88/03559. Reassorted immunoglobulin chains also are known. See, forexample, U.S. Pat. No. 4,444,878; WO 88/03565; and EP 68,763 andreferences cited therein.

In one embodiment, the modified antibodies of the invention areminibodies. Minibodies are dimeric molecules made up of two polypeptidechains each comprising an ScFv molecule (a single polypeptide comprisingone or more antigen binding sites, e.g., a VL domain linked by aflexible linker to a VH domain fused to a CH3 domain via a connectingpeptide.

ScFv molecules can be constructed in a VH-linker-VL orientation orVL-linker-VH orientation.

The flexible hinge that links the VL and VH domains that make up theantigen binding site preferably comprises from about 10 to about 50amino acid residues. An exemplary connecting peptide for this purpose is(Gly4Ser)3 (SEQ ID NO:20) (Huston et al. 1988. Proc. Natl. Acad. Sci.USA 85:5879). Other connecting peptides are known in the art.

Methods of making single chain antibodies are well known in the art,e.g., Ho et al. 1989. Gene 77:51; Bird et al. 1988 Science 242:423;Pantoliano et al. 1991. Biochemistry 30:10117; Milenic et al. 1991.Cancer Research 51:6363; Takkinen et al. 1991. Protein Engineering4:837.

Minibodies can be made by constructing an ScFv component and connectingpeptide-CH3 component using methods described in the art (see, e.g.,U.S. Pat. No. 5,837,821 or WO 94/09817A1). These components can beisolated from separate plasmids as restriction fragments and thenligated and recloned into an appropriate vector. Appropriate assemblycan be verified by restriction digestion and DNA sequence analysis.

Diabodies are similar to scFv molecules, but usually have a short (lessthan 10 and preferably 1-5) amino acid residue linker connecting bothV-domains, such that the VL and VH domains on the same polypeptide chaincan not interact. Instead, the VL and VH domain of one polypeptide chaininteract with the VH and VL domain (respectively) on a secondpolypeptide chain (WO 02/02781). In one embodiment, a binding moleculeof the invention is a diabody fused to at least one heavy chain portion.In a preferred embodiment, a binding molecule of the invention is adiabody fused to a CH3 domain.

Other forms of modified antibodies are also within the scope of theinstant invention (e.g., WO 02/02781 A1; U.S. Pat. No. 5,959,083;6,476,198 B1; US 2002/0103345 A1; WO 00/06605; Byrn et al. 1990. Nature.344:667-70; Chamow and Ashkenazi. 1996. Trends Biotechnol. 14:52).

In one embodiment, a binding molecule of the invention comprises animmunoglobulin constant region. It is known in the art that the constantregion mediates several effector functions. For example, binding of theC1 component of complement to binding molecules activates the complementsystem. Activation of complement is important in the opsonisation andlysis of cell pathogens. The activation of complement also stimulatesthe inflammatory response and may also be involved in autoimmunehypersensitivity. Further, binding molecules bind to cells via the Fcregion, with a Fc receptor site on the binding molecule Fc regionbinding to a Fc receptor (FcR) on a cell. There are a number of Fcreceptors which are specific for different classes of binding molecule,including IgG (gamma receptors), IgE (epsilon receptors), IgA (alphareceptors) and IgM (mu receptors). Binding of binding molecule to Fcreceptors on cell surfaces triggers a number of important and diversebiological responses including engulfment and destruction of bindingmolecule-coated particles, clearance of immune complexes, lysis ofbinding molecule-coated target cells by killer cells (calledantibody-dependent cell-mediated cytotoxicity, or ADCC), release ofinflammatory mediators, placental transfer and control of immunoglobulinproduction.

In one embodiment, effector functions may be eliminated or reduced byusing a constant region of an IgG4 binding molecule, which is thought tobe unable to deplete target cells, or making Fe variants, whereinresidues in the Fc region critical for effector function(s) are mutatedusing techniques known in the art, for example, U.S. Pat. No. 5,585,097.For example, the deletion or inactivation (through point mutations orother means) of a constant region domain may reduce Fc receptor bindingof the circulating modified binding molecule thereby increasing tumorlocalization. In other cases it may be that constant regionmodifications consistent with the instant invention moderate complimentbinding and thus reduce the serum half life and nonspecific associationof a conjugated cytotoxin. Yet other modifications of the constantregion may be used to modify disulfide linkages or oligosaccharidemoieties that allow for enhanced localization due to increased antigenspecificity or binding molecule flexibility. More generally, thoseskilled in the art will realize that binding molecules modified asdescribed herein may exert a number of subtle effects that may or maynot be readily appreciated. However the resulting physiological profile,bioavailability and other biochemical effects of the modifications, suchas tumor localization, biodistribution and serum half-life, may easilybe measured and quantified using well know immunological techniqueswithout undue experimentation.

In one embodiment, a binding molecule of the invention can bederivatized or linked to another functional molecule (e.g., anotherpeptide or protein). Accordingly, a binding molecule of the inventioninclude derivatized and otherwise modified forms of the anti-ILT3binding molecules described herein, including immunoadhesion molecules.For example, a binding molecule of the invention can be functionallylinked (by chemical coupling, genetic fusion, noncovalent association orotherwise) to one or more other molecular entities, such as anotherbinding molecule (e.g., a bispecific antibody or a diabody), adetectable agent, a cytotoxic agent, a pharmaceutical agent, and/or aprotein or peptide that can mediate association of the binding moleculewith another molecule (such as a streptavidin core region or apolyhistidine tag).

One type of derivatized binding molecule is produced by crosslinking twoor more binding molecules (of the same type or of different types, e.g.,to create bispecific antibodies). Suitable crosslinkers include thosethat are heterobifunctional, having two distinctly reactive groupsseparated by an appropriate spacer (e.g.,m-maleimidobenzoyl-N-hydroxysuccinimide ester) or homobifunctional(e.g., disuccinimidyl suberate). Such linkers are available from PierceChemical Company, Rockford, Ill.

Useful detectable agents with which a binding molecule of the inventionmay be derivatized include fluorescent compounds. Exemplary fluorescentdetectable agents include fluorescein, fluorescein isothiocyanate,rhodamine, 5-dimethylamine-1-napthalenesulfonyl chloride, phycoerythrinand the like. A binding molecule may also be derivatized with detectableenzymes, such as alkaline phosphatase, horseradish peroxidase, glucoseoxidase and the like. When a binding molecule is derivatized with adetectable enzyme, it is detected by adding additional reagents that theenzyme uses to produce a detectable reaction product. For example, whenthe detectable agent horseradish peroxidase is present, the addition ofhydrogen peroxide and diaminobenzidine leads to a colored reactionproduct, which is detectable. A binding molecule may also be derivatizedwith biotin, and detected through indirect measurement of avidin orstreptavidin binding.

IV. Expression of Binding Molecules

A binding molecule of the invention can be prepared by recombinantexpression of immunoglobulin light and heavy chain genes in a host cell.To express a binding molecule recombinantly, a host cell is transfectedwith one or more recombinant expression vectors carrying DNA fragmentsencoding the immunoglobulin light and heavy chains of the bindingmolecule such that the light and heavy chains are expressed in the hostcell and, preferably, secreted into the medium in which the host cellsare cultured, from which medium a binding molecule can be recovered.Standard recombinant DNA methodologies are used to obtain antibody heavyand light chain genes, incorporate these genes into recombinantexpression vectors, and introduce the vectors into host cells, such asthose described in Sambrook, Fritsch and Maniatis (eds), MolecularCloning; A Laboratory Manual, Second Edition, Cold Spring Harbor, N.Y.,(1989), Ausubel, F. M. et al. (eds.) Current Protocols in MolecularBiology, Greene Publishing Associates, (1989) and in U.S. Pat. No.4,816,397 by Boss, et al.

To express a binding molecule of the invention, DNAs encoding partial orfull-length light and heavy chains may be inserted into expressionvectors such that the genes are operatively linked to transcriptionaland translational control sequences. In this context, the term“operatively linked” means that a binding molecule gene is ligated intoa vector such that transcriptional and translational control sequenceswithin the vector serve their intended function of regulating thetranscription and translation of the binding molecule gene. In oneembodiment, the expression vector and expression control sequences arechosen to be compatible with the expression host cell used. The bindingmolecule light chain gene and the binding molecule heavy chain gene maybe inserted into separate vector or, more typically, both genes areinserted into the same expression vector. The binding molecule genes maybe inserted into the expression vector by standard methods (e.g.,ligation of complementary restriction sites on the binding molecule genefragment and vector, or blunt end ligation if no restriction sites arepresent). Prior to insertion of the binding molecule light or heavychain sequences, the expression vector may already carry bindingmolecule constant region sequences. For example, one approach toconverting VH and VL sequences to full-length binding molecule genes isto insert them into expression vectors already encoding heavy chainconstant and light chain constant regions, respectively, such that theVH segment is operatively linked to the CH segment(s) within the vectorand the VL segment is operatively linked to the CL segment within thevector. Additionally or alternatively, the recombinant expression vectorcan encode a signal peptide that facilitates secretion of the bindingmolecule chain from a host cell. The binding molecule chain gene can becloned into the vector such that the signal peptide is linked in-frameto the amino terminus of the binding molecule chain gene. The signalpeptide can be an immunoglobulin signal peptide or a heterologous signalpeptide (i.e., a signal peptide from a non-immunoglobulin protein).

In addition to the binding molecule chain genes, the recombinantexpression vectors of the invention carry regulatory sequences thatcontrol the expression of the binding molecule chain genes in a hostcell. The term “regulatory sequence” includes promoters, enhancers andother expression control elements (e.g., polyadenylation signals) thatcontrol the transcription or translation of the binding molecule chaingenes. Such regulatory sequences are described, for example, in Goeddel;Gene Expression Technology: Methods in Enzymology 185, Academic Press,San Diego, Calif. (1990). It will be appreciated by those skilled in theart that the design of the expression vector, including the selection ofregulatory sequences may depend on such factors as the choice of thehost cell to be transformed, the level of expression of protein desired,etc. Preferred regulatory sequences for mammalian host cell expressioninclude viral elements that direct high levels of protein expression inmammalian cells, such as promoters and/or enhancers derived fromcytomegalovirus (CMV) (such as the CMV promoter/enhancer), Simian Virus40 (SV40) (such as the SV40 promoter/enhancer), adenovirus, (e.g., theadenovirus major late promoter (AdMLP) and polyoma. For furtherdescription of viral regulatory elements, and sequences thereof, seee.g., U.S. Pat. No. 5,168,062 by Stinski, U.S. Pat. No. 4,510,245 byBell et al. and U.S. Pat. No. 4,968,615 by Schaffner, et al.

In addition to the binding molecule chain genes and regulatorysequences, the recombinant expression vectors of the invention may carryadditional sequences, such as sequences that regulate replication of thevector in host cells (e.g., origins of replication) and selectablemarker genes. The selectable marker gene facilitates selection of hostcells into which the vector has been introduced (see e.g., U.S. Pat.Nos. 4,399,216, 4,634,665 and 5,179,017, all by Axel et al.). Forexample, typically the selectable marker gene confers resistance todrugs, such as G418, hygromycin or methotrexate, on a host cell intowhich the vector has been introduced. Preferred selectable marker genesinclude the dihydrofolate reductase (DHFR) gene (for use in dhfr⁻ hostcells with methotrexate selection/amplification) and the neo gene (forG418 selection).

For expression of the light and heavy chains, the expression vector(s)encoding the binding molecule heavy and light chains is transfected intoa host cell by standard techniques. The various forms of the term“transfection” are intended to encompass a wide variety of techniquescommonly used for the introduction of exogenous DNA into a prokaryoticor eukaryotic host cell, e.g., electroporation, calcium-phosphateprecipitation, DEAE-dextran transfection and the like. It is possible toexpress a binding molecule of the invention in either prokaryotic oreukaryotic host cells, expression of binding molecules in eukaryoticcells, and most preferably mammalian host cells, is the most preferredbecause such eukaryotic cells, and in particular mammalian cells, aremore likely than prokaryotic cells to assemble and secrete a properlyfolded and immunologically active binding molecule.

Commonly, expression vectors contain selection markers (e.g.,ampicillin-resistance, hygromycin-resistance, tetracycline resistance orneomycin resistance) to permit detection of those cells transformed withthe desired DNA sequences (see, e.g., Itakura et al., U.S. Pat. No.4,704,362).

E. coli is one prokaryotic host particularly useful for cloning thepolynucleotides (e.g., DNA sequences) of the present invention. Othermicrobial hosts suitable for use include bacilli, such as Bacillussubtilus, and other enterobacteriaceae, such as Salmonella, Serratia,and various Pseudomonas species. In these prokaryotic hosts, one canalso make expression vectors, which will typically contain expressioncontrol sequences compatible with the host cell (e.g., an origin ofreplication). In addition, any number of a variety of well-knownpromoters will be present, such as the lactose promoter system, atryptophan (trp) promoter system, a beta-lactamase promoter system, or apromoter system from phage lambda. The promoters will typically controlexpression, optionally with an operator sequence, and have ribosomebinding site sequences and the like, for initiating and completingtranscription and translation.

Other microbes, such as yeast, are also useful for expression.Saccharomyces is a preferred yeast host, with suitable vectors havingexpression control sequences (e.g., promoters), an origin ofreplication, termination sequences and the like as desired. Typicalpromoters include 3-phosphoglycerate kinase and other glycolyticenzymes. Inducible yeast promoters include, among others, promoters fromalcohol dehydrogenase, isocytochrome C, and enzymes responsible formaltose and galactose utilization.

In addition to microorganisms, mammalian tissue cell culture may also beused to express and produce the polypeptides of the present invention(e.g., polynucleotides encoding binding molecules). See Winnacker, FromGenes to Clones, VCH Publishers, N.Y., N.Y. (1987). Eukaryotic cells areactually preferred, because a number of suitable host cell lines capableof secreting heterologous proteins (e.g., intact binding molecules) havebeen developed in the art, and include CHO cell lines, various Cos celllines, HeLa cells, myeloma cell lines, or transformed B-cells orhybridomas. Preferably, the cells are nonhuman. Expression vectors forthese cells can include expression control sequences, such as an originof replication, a promoter, and an enhancer (Queen et al., Immunol. Rev.89:49 (1986)), and necessary processing information sites, such asribosome binding sites, RNA splice sites, polyadenylation sites, andtranscriptional terminator sequences. Preferred expression controlsequences are promoters derived from immunoglobulin genes, SV40,adenovirus, bovine papilloma virus, cytomegalovirus and the like. See Coet al., J. Immunol. 148:1149 (1992).

Alternatively, binding molecule-coding sequences can be incorporated intransgenes for introduction into the genome of a transgenic animal andsubsequent expression in the milk of the transgenic animal (see, e.g.,Deboer et al., U.S. Pat. No. 5,741,957, Rosen, U.S. Pat. No. 5,304,489,and Meade et al., U.S. Pat. No. 5,849,992). Suitable transgenes includecoding sequences for light and/or heavy chains in operable linkage witha promoter and enhancer from a mammary gland specific gene, such ascasein or beta lactoglobulin.

Preferred mammalian host cells for expressing the recombinant bindingmolecules of the invention include Chinese Hamster Ovary (CHO cells)(including dhfr− CHO cells, described in Urlaub and Chasin, (1980) Proc.Natl. Acad. Sci. USA 77:4216-4220, used with a DHFR selectable marker,e.g., as described in R. J. Kaufman and P. A. Sharp (1982) Mol. Biol.159:601-621), NS0 myeloma cells, COS cells and SP2 cells. Whenrecombinant expression vectors encoding binding molecule genes areintroduced into mammalian host cells, binding molecules are produced byculturing the host cells for a period of time sufficient to allow forexpression of the binding molecule in the host cells or, morepreferably, secretion of the binding molecule into the culture medium inwhich the host cells are grown. Binding molecules can be recovered fromthe culture medium using standard protein purification methods.

The vectors containing the polynucleotide sequences of interest (e.g.,the binding molecule heavy and light chain encoding sequences andexpression control sequences) can be transferred into the host cell bywell-known methods, which vary depending on the type of cellular host.For example, calcium chloride transfection is commonly utilized forprokaryotic cells, whereas calcium phosphate treatment, electroporation,lipofection, biolistics or viral-based transfection may be used forother cellular hosts. (See generally Sambrook et al., Molecular Cloning:A Laboratory Manual (Cold Spring Harbor Press, 2nd ed., 1989)(incorporated by reference in its entirety for all purposes). Othermethods used to transform mammalian cells include the use of polybrene,protoplast fusion, liposomes, electroporation, and microinjection (seegenerally, Sambrook et al., supra). For production of transgenicanimals, transgenes can be microinjected into fertilized oocytes, or canbe incorporated into the genome of embryonic stem cells, and the nucleiof such cells transferred into enucleated oocytes.

When heavy and light chains are cloned on separate expression vectors,the vectors are co-transfected to obtain expression and assembly ofintact immunoglobulins. Once expressed, the whole binding molecules,their dimers, individual light and heavy chains, or other immunoglobulinforms of the present invention can be purified according to standardprocedures of the art, including ammonium sulfate precipitation,affinity columns, column chromatography, HPLC purification, gelelectrophoresis and the like (see generally Scopes, Protein Purification(Springer-Verlag, N.Y., (1982)). Substantially pure binding molecules ofat least about 90 to 95% homogeneity are preferred, and 98 to 99% ormore homogeneity most preferred, for pharmaceutical uses.

Host cells can also be used to produce portions of intact bindingmolecules, such as Fab fragments or scFv molecules. It will beunderstood that variations on the above procedure are within the scopeof the present invention. For example, it may be desirable to transfecta host cell with DNA encoding either the light chain or the heavy chain(but not both) of a binding molecule of this invention. Recombinant DNAtechnology may also be used to remove some or all of the DNA encodingeither or both of the light and heavy chains that is not necessary forbinding to ILT3. The molecules expressed from such truncated DNAmolecules are also encompassed by a binding molecule of the invention.In addition, bifunctional binding molecules may be produced in which oneheavy and one light chain are a binding molecule of the invention andthe other heavy and light chain are specific for an antigen other thanILT3 by crosslinking a binding molecule of the invention to a secondbinding molecule by standard chemical crosslinking methods.

In view of the foregoing, another aspect of the invention pertains tonucleic acid, vector and host cell compositions that can be used forrecombinant expression of the binding molecules of the invention. Thenucleotide sequence encoding the 9B11 light chain variable region isshown in SEQ ID NO: 10. The CDR1 domain of the VL encompassesnucleotides 130-162, the CDR2 domain encompasses nucleotides 208-228,and the CDR3 domain encompasses nucleotides 325-351 of SEQ ID NO:10. Thenucleotide sequence encoding the 9B11 heavy chain variable region isalso shown in SEQ ID NO: 9. The CDR1 domain of the VH encompassesnucleotides 133-162, the CDR2 domain encompasses nucleotides 205-255,and the CDR3 domain encompasses nucleotides 352-372 of SEQ ID NO:9. Itwill be appreciated by the skilled artisan that nucleotide sequencesencoding 9B11-related binding molecule can be derived from thenucleotide sequences encoding the 9B11 LCVR and HCVR using the geneticcode and standard molecular biology techniques.

In one embodiment, the invention provides isolated nucleic acidsencoding a 9B11-related CDR domain, e.g., comprising an amino acidsequence selected from the group consisting of: SEQ ID NO: 3, SEQ ID NO:4, SEQ ID NO: 5, SEQ ID NO: 6, SEQ ID NO: 7, and SEQ ID NO: 8.

In still another embodiment, the invention provides an isolated nucleicacid encoding a binding molecule light chain variable region comprisingthe amino acid sequence of SEQ ID NO: 2, although the skilled artisanwill appreciate that due to the degeneracy of the genetic code, othernucleotide sequences can encode the amino acid sequence of SEQ ID NO: 2.The nucleic acid can encode only the VL or can also encode a bindingmolecule light chain constant region, operatively linked to the VL. Inone embodiment, this nucleic acid is in a recombinant expression vector.

In still another embodiment, the invention provides an isolated nucleicacid encoding a binding molecule heavy chain variable region comprisingthe amino acid sequence of SEQ ID NO: 1, although the skilled artisanwill appreciate that due to the degeneracy of the genetic code, othernucleotide sequences can encode the amino acid sequence of SEQ ID NO: 1.The nucleic acid can encode only the VH or can also encode a heavy chainconstant region, operatively linked to the VH. For example, the nucleicacid can comprise an IgG1 or IgG2 constant region. In one embodiment,this nucleic acid is in a recombinant expression vector.

The invention also provides recombinant expression vectors encoding abinding molecule heavy chain and/or a binding molecule light chain. Forexample, in one embodiment, the invention provides a recombinantexpression vector encoding:

-   -   a) a binding molecule light chain having a variable region        comprising the amino acid sequence of SEQ ID NO: 2; and    -   b) a binding molecule heavy chain having a variable region        comprising the amino acid sequence of SEQ ID NO: 1.

In another embodiment, the invention provides a recombinant expressionvector encoding:

-   -   a) a binding molecule light chain having a variable region        comprising the amino acid sequence of SEQ ID NO: 28; and    -   b) a binding molecule heavy chain having a variable region        comprising the amino acid sequence of SEQ ID NO: 29.

In one embodiment, the invention provides a recombinant expressionvector encoding:

-   -   a) a binding molecule light chain having a variable region        comprising the amino acid sequence of SEQ ID NO: 25; and    -   b) a binding molecule heavy chain having a variable region        comprising the amino acid sequence of SEQ ID NO: 26.

In yet another embodiment, the invention provides a recombinantexpression vector encoding:

-   -   a) a binding molecule light chain having a variable region        comprising the amino acid sequence of SEQ ID NO: 25; and    -   b) a binding molecule heavy chain having a variable region        comprising the amino acid sequence of SEQ ID NO: 27.

In another embodiment, the invention provides a recombinant expressionvector encoding:

-   -   a) a binding molecule light chain having a variable region        comprising the amino acid sequence of SEQ ID NO: 33; and    -   b) a binding molecule heavy chain having a variable region        comprising the amino acid sequence of SEQ ID NO: 34.    -   In yet another embodiment, the invention provides a recombinant        expression vector encoding:    -   a) a binding molecule light chain having a variable region        comprising the amino acid sequence of SEQ ID NO: 33; and    -   b) a binding molecule heavy chain having a variable region        comprising the amino acid sequence of SEQ ID NO: 35.

The invention also provides host cells into which one or more of therecombinant expression vectors of the invention have been introduced.Preferably, the host cell is a mammalian host cell.

Still further the invention provides a method of synthesizing arecombinant binding molecule of the invention by culturing a host cellof the invention in a suitable culture medium until a recombinantbinding molecule of the invention is synthesized. The method can furthercomprise isolating the recombinant binding molecule from the culturemedium.

V. Uses of the Binding Molecules of the Invention

Given their ability to bind to ILT3, the binding molecules of theinvention can be used to detect ILT3 (e.g., in a biological sample, suchas serum or plasma), using a conventional immunoassay, such as an enzymelinked immunosorbent assays (ELISA), an radioimmunoassay (RIA) or tissueimmunohistochemistry. The invention provides a method for detectinghILT3 in a biological sample comprising contacting a biological samplewith a binding molecule of the invention and detecting either thebinding molecule bound to hILT3 or unbound binding molecule, to therebydetect hILT3 in the biological sample. The binding molecule is directlyor indirectly labeled with a detectable substance to facilitatedetection of the bound or unbound binding molecule. Suitable detectablesubstances include various enzymes, prosthetic groups, fluorescentmaterials, luminescent materials and radioactive materials. Examples ofsuitable enzymes include horseradish peroxidase, alkaline phosphatase,β-galactosidase, or acetylcholinesterase; examples of suitableprosthetic group complexes include streptavidin/biotin andavidin/biotin; examples of suitable fluorescent materials includeumbelliferone, fluorescein, fluorescein isothiocyanate, rhodamine,dichlorotriazinylamine fluorescein, dansyl chloride or phycoerythrin; anexample of a luminescent material includes luminol; and examples ofsuitable radioactive material include ¹²⁵I, ¹³¹I, ³⁵S or ³H.

Alternative to labeling the binding molecule, hILT3 can be assayed inbiological fluids by a competition immunoassay utilizing ILT3 standardslabeled with a detectable substance and an unlabeled anti-hILT3 bindingmolecule. In this assay, the biological sample, the labeled ILT3standards and the anti-hILT3 binding molecule are combined and theamount of labeled ILT3 standard bound to the unlabeled binding moleculeis determined. The amount of hILT3 in the biological sample is inverselyproportional to the amount of labeled ILT3 standard bound to theanti-hILT3 binding molecule.

An anti-ILT3 binding molecule of the invention can also be used todetect ILT3s from species other than humans, in particular ILT3s fromprimates (e.g., chimpanzee, baboon, marmoset, cynomolgus and rhesus).

Methods of Downmodulating Immune Responses In Vitro and In Vivo

As described in the appended examples, the binding molecules of theinvention can be used as immunoinhibitory compositions in vitro toinhibit immune cell activation, such as an alloimmune response (e.g., anMLC), by cells. In one embodiment, cells are treated with an ILT-3binding molecule in vitro, e.g., for one, two, three, four, five, six,seven days, e.g., to reduce their state of activation prior to theirinfusion into a subject.

Accordingly, in one embodiment, the invention provides a method formodulating, e.g., downmodulating, immune cell activation, e.g., analloimmune response, in vitro. In another embodiment, the inventionprovides a method of downmodulating immune cell activation in vivocomprising introducing cells treated in vitro with an ILT-3 bindingmolecule into a subject. Modulation of an alloimmune response can beassayed using art recognized techniques, for example, by measuring theability of the binding molecule to modulate the proliferative ability ofT cells, e.g., in a mixed lymphocyte reaction.

The binding molecules of the invention may also be used to downmodulatethe production of inflammatory cytokines, e.g., IL12p40, IL12p70, andTNFα, by DC, e.g., MDDC, in vitro, e.g., prior to introduction into asubject. Downmodulation of inflammatory cytokine production by DC can beassayed, for example, by ELISA.

In another embodiment, the binding molecules of the invention may alsobe used to downmodulate the upregulation of costimulatory molecules,e.g., CD86, CD80, CD83, and HLA-DR, by DC, e.g., MDDC, in vitro, e.g.,prior to introduction into a subject. Downmodulation of the upregulationof costimulatory molecules by DC can be assayed, for example, by FACsanalysis.

In yet another embodiment, the binding molecules of the invention mayalso be used to downmodulate calcium flux in monocytes in vitro, e.g.,prior to their introduction into a subject. Calcium flux in monocytescan be measured, for example, by FACs analysis or by calcium-chelationluminescence spectrophotometry. See for example, Rabin, et al. (1999) JImmunol. 162:3840-3850, Youn, B. S., et al. (1998) Blood 91:3118, andYoun, B. S., et al. (1997) J. Immunol. 159:5201, the contents of each ofthese references is hereby incorporated herein by reference.

In one embodiment, the binding molecules of the invention may be used toupregulate the expression of inhibitory receptors on a cell, such as adendritic cell, e.g., an immature dendritic cell. Exemplary inhibitoryreceptors whose expression is upregulated by the binding molecules ofthe invention include, but are not limited to, CD200R, CD40L and IDO(indolamine).

In one aspect, the invention relates to a method for preventing in asubject, a disease or condition associated with unwanted immune cellactivation comprising treating cells in vitro with an ILT-3 bindingagent and introducing them into a compatible subject or reintroducingthem into the same subject. Subjects at risk for a disease that wouldbenefit from treatment with the claimed agents or methods can beidentified, for example, by any or a combination of diagnostic orprognostic assays known in the art. Administration of a prophylacticagent can occur prior to the manifestation of symptoms associated withan unwanted or less than desirable immune response.

Diseases or pathological conditions that would benefit fromdownmodulating the activity of ILT3 on APC, e.g., monocytes,macrophages, and DC, e.g., MDDC, include situations of tissue, skin andorgan transplantation or graft-versus-host disease (GVHD). For example,blockage of immune cell activation results in reduced tissue destructionin tissue transplantation. Typically, in tissue transplants, rejectionof the transplant is initiated through its recognition as foreign byimmune cells, followed by an immune reaction that destroys thetransplant. The cells treated in vitro with an anti-ILT3 bindingmolecule can be administered alone or in conjunction with another agentwhich downmodulates immune cell activation, prior to or at the time oftransplantation to reduce immune cell activation to the transplant(e.g., hormonal therapy, immunotherapy, e.g., immunosuppressive therapy,antibiotics, and immunoglobulin). Generally, administration of productsof a species origin or species reactivity (in the case of bindingmolecules) that is the same species as that of the patient is preferred.It may also be desirable to block the costimulatory function of otherpolypeptides. For example, it may be desirable to block the function ofB7-1, B7-2, or B7-1 and B7-2 by administering a soluble form of acombination of peptides having an activity of each of these antigens,blocking antibodies against these antigens or blocking small molecules(separately or together in a single composition) prior to or at the timeof transplantation. Other downmodulatory agents that can be used inconnection with the downmodulatory methods of the invention include, forexample, agents that transmit an inhibitory signal via CTLA4, solubleforms of CTLA4, antibodies that activate an inhibitory signal via CTLA4,blocking antibodies against other immune cell markers or soluble formsof other receptor ligand pairs (e.g., agents that disrupt theinteraction between CD40 and CD40 ligand (e.g., anti CD40 ligandantibodies)), antibodies against cytokines, or immunosuppressive drugs.

Moreover, modulation of ILT3, and/or inhibition of costimulatorysignals, and/or upregulation of other inhibitory receptors, may also besufficient to anergize the immune cells, thereby inducing tolerance in asubject. Induction of long-term tolerance by modulating ILT3 may avoidthe necessity of repeated administration of these blocking reagents.

Accordingly, the methods of the invention can be used to treat a subjectsuffering from a disorder, which method comprises contacting a cell froma subject with a binding molecule of the invention such that an immuneresponse is downmodulated. Preferably, the subject is a human subject.Alternatively, the subject can be a mammal expressing ILT3 with which abinding molecule of the invention cross-reacts.

Methods of Upmodulating Immune Responses In Vivo

As described in the appended examples, the binding molecules of theinvention can be used as immunostimulatory compositions, e.g., alone oras part of a vaccine, to promote B cell, and/or T cell activation, e.g.,either Th1 or Th2 cell activation, in a subject. That is, the bindingmolecules of the invention can serve as adjuvants used in combinationwith an antigen of interest to enhance an immune response to thatantigen of interest in vivo. For example, to stimulate an antibody orcellular immune response to an antigen of interest (e.g., forvaccination purposes), the antigen and a binding molecules of theinvention can be coadministered (e.g., coadministered at the same timein the same or separate compositions, or sequentially in time such thatan enhanced immune response occurs). The antigen of interest and thebinding molecules can be formulated together into a singlepharmaceutical composition or in separate compositions. In a preferredembodiment, the antigen of interest and the binding molecule areadministered simultaneously to the subject. Alternatively, in certainsituations it may be desirable to administer the antigen first and thenthe binding molecule or vice versa (for example, in the case of anantigen that naturally evokes a Th1 response, it may be beneficial tofirst administer the antigen alone to stimulate a Th1 response and thenadminister a binding molecule, alone or together with a boost ofantigen, to shift the immune response to a Th2 response). In preferredembodiments, an ILT3 binding molecule of the invention is administeredat the time of priming with antigen, i.e., at the time of the firstadministration of antigen. For example, day −3, −2, −1, 0, +1, +2, +3. Aparticularly preferred day of administration of an ILT3 binding moleculeof the invention is day −1.

In one embodiment, an ILT-3 binding molecule is administered with anantigen of interest. An antigen of interest is one to which an immuneresponse is desired. For example, one capable of providing protection insubject against challenge by an infectious agent from which the antigenwas derived. In another embodiment, the invention pertains toadministration of an ILT-3 binding molecule of the invention to increaseimmune responses without having to administer an antigen.

Exemplary antigens of interest therefore include those derived frominfectious agents, wherein an immune response directed against theantigen serves to prevent or treat disease caused by the agent. Suchantigens include, but are not limited to, viral, bacterial, fungal orparasite proteins and any other proteins, glycoproteins, lipoprotein,glycolipids, and the like. Antigens of interest also include those whichprovide benefit to a subject which is at risk for acquiring or which isdiagnosed as having a tumor. The subject is preferably a mammal and mostpreferably, is a human.

Typical antigens of interest may be classified as follows: proteinantigens, such as ceruloplasmin and serum albumin; bacterial antigens,such as teichoic acids, flagellar antigens, capsular polysaccharides,and extra-cellular bacterial products and toxins; glycoproteins andglycolipids; viruses, such as animal, plant, and bacterial viruses;conjugated and synthetic antigens, such as proteinhapten conjugates,molecules expressed preferentially by tumors, compared to normal tissue;synthetic polypeptides; and nucleic acids, such as ribonucleic acid anddeoxyribonucleic acid. The term “infectious agent,” as used herein,includes any agent which expresses an antigen which elicits a hostcellular immune response. Non-limiting examples of viral antigens whichmay be considered useful as include, but are not limited to, thenucleoprotein (NP) of influenza virus and the Gag proteins of HIV. Otherheterologous antigens include, but are not limited to, HIV Env proteinor its component parts gp120 and gp41, HIV Nef protein, and the HIV Polproteins, reverse transcriptase and protease. In addition, other viralantigens such as Ebola virus (EBOV) antigens, such as, for example, EBOVNP or glycoprotein (GP), either full-length or GP deleted in the mucinregion of the molecule (Yang Z-Y, et al. (2000) Nat Med 6:886-9, 2000),small pox antigens, hepatitis A, B or C virus, human rhinovirus such astype 2 or type 14, Herpes simplex virus, poliovirus type 2 or 3,foot-and-mouth disease virus (FMDV), rabies virus, rotavirus, influenzavirus, coxsackie virus, human papilloma virus (HPV), for example thetype 16 papilloma virus, the E7 protein thereof, and fragmentscontaining the E7 protein or its epitopes; and simian immunodeficiencyvirus (SW) may be used. The antigens of interest need not be limited toantigens of viral origin. Parasitic antigens, such as, for example,malarial antigens are included, as are fungal antigens, bacterialantigens and tumor antigens. Examples of antigens derived from bacteriaare those derived from Bordetella pertussis (e.g., P69 protein andfilamentous haemagglutinin (FHA) antigens), Vibrio cholerae, Bacillusanthracis, and E. coli antigens such as E. coli heat Labile toxin Bsubunit (LT-B), E. coli K88 antigens, and enterotoxigenic E. coliantigens. Other examples of antigens include Schistosoma mansoni P28glutathione S-transferase antigens (P28 antigens) and antigens offlukes, mycoplasma, roundworms, tapeworms, Chlamydia trachomatis, andmalaria parasites, e.g., parasites of the genus plasmodium or babesia,for example Plasmodium falciparum, and peptides encoding immunogenicepitopes from the aforementioned antigens.

By the term “tumor-related antigen,” as used herein, is meant an antigenwhich affects tumor growth or metastasis in a host organism. Thetumor-related antigen may be an antigen expressed by a tumor cell, or itmay be an antigen which is expressed by a non-tumor cell, but which whenso expressed, promotes the growth or metastasis of tumor cells. Thetypes of tumor antigens and tumor-related antigens include any known orheretofore unknown tumor antigen, including, without limitation, thebcr/abl antigen in leukemia, HPVE6 and E7 antigens of the oncogenicvirus associated with cervical cancer, the MAGE1 and MZ2-E antigens inor associated with melanoma, and the MVC-1 and HER-2 antigens in orassociated with breast cancer.

An infection, disease or disorder which may be treated or prevented bythe administration of a composition of the invention includes anyinfection, disease or disorder wherein a host immune response acts toprevent the infection, disease or disorder. Diseases, disorders, orinfection which may be treated or prevented by the administration of thecompositions of the invention include, but are not limited to, anyinfection, disease or disorder caused by or related to a fungus,parasite, virus, or bacteria, diseases, disorders or infections causedby or related to various agents used in bioterrorism, listeriosis, Ebolavirus, SARS, small pox, hepatitis A, hepatitis B, hepatitis C, diseasesand disorders caused by human rhinovirus, HIV and AIDS, Herpes, polio,foot-and-mouth disease, rabies, diseases or disorders caused by orrelated to: rotavirus, influenza, coxsackie virus, human papillomavirus, SIV, malaria, cancer, e.g., tumors, and diseases or disorderscaused by or related to infection by Bordetella pertussis, Vibriocholerae, Bacillus anthracis, E. coli, flukes, mycoplasma, roundworms,tapeworms, Chlamydia trachomatis, and malaria parasites, etc.

Immune Responses to Tumor Cells

Regulatory T cells play an important role in the maintenance ofimmunological self-tolerance by suppressing immune responses againstautoimmune diseases and cancer. Accordingly, in one embodiment,upmodulating an immune response would be beneficial for enhancing animmune response in cancer. Therefore, the binding molecules of theinvention can be used in the treatment of malignancies, to inhibit tumorgrowth or metastasis. The binding molecules may be administeredsystemically or locally to the tumor site.

In one embodiment, modulation of ILT3 function may be useful in theinduction of tumor immunity. An ILT3 binding molecule can beadministered to a patient having tumor cells (e.g., sarcoma, melanoma,lymphoma, leukemia, neuroblastoma, carcinoma) to overcome tumor-specifictolerance in the subject.

As used herein, the term “neoplastic disease” is characterized bymalignant tumor growth or in disease states characterized by benignhyperproliferative and hyperplastic cells. The common medical meaning ofthe term “neoplasia” refers to “new cell growth” that results as a lossof responsiveness to normal growth controls, e.g., neoplastic cellgrowth.

As used herein, the terms “hyperproliferative”, “hyperplastic”,malignant” and “neoplastic” are used interchangeably, and refer to thosecells in an abnormal state or condition characterized by rapidproliferation or neoplasia. The terms are meant to include all types ofhyperproliferative growth, hyperplastic growth, cancerous growths oroncogenic processes, metastatic tissues or malignantly transformedcells, tissues, or organs, irrespective of histopathologic type or stageof invasiveness. A “hyperplasia” refers to cells undergoing anabnormally high rate of growth. However, as used herein, the termsneoplasia and hyperplasia can be used interchangeably, as their contextwill reveal, referring generally to cells experiencing abnormal cellgrowth rates. Neoplasias and hyperplasias include “tumors,” which may beeither benign, premalignant or malignant.

The terms “neoplasia,” “hyperplasia,” and “tumor” are often commonlyreferred to as “cancer,” which is a general name for more than 100disease that are characterized by uncontrolled, abnormal growth ofcells. Examples of cancer include, but are not limited to: breast;colon; non-small cell lung, head and neck; colorectal; lung; prostate;ovary; renal; melanoma; and gastrointestinal (e.g., pancreatic andstomach) cancer; and osteogenic sarcoma.

In one embodiment, the cancer is selected from the group consisting of:pancreatic cancer, melanomas, breast cancer, lung cancer, bronchuscancer, colorectal cancer, prostate cancer, pancreas cancer, stomachcancer, ovarian cancer, urinary bladder cancer, brain or central nervoussystem cancer, peripheral nervous system cancer, esophageal cancer,cervical cancer, uterine or endometrial cancer, cancer of the oralcavity or pharynx, liver cancer, kidney cancer, testicular cancer,biliary tract cancer, small bowel or appendix cancer, salivary glandcancer, thyroid gland cancer, adrenal gland cancer, osteosarcoma,chondrosarcoma, cancer of hematological tissues.

Immune Responses to Infectious Agents

Upregulation of immune responses may be in the form of enhancing anexisting immune response or eliciting an initial immune response. Forexample, enhancing an immune response by modulation of ILT3 may beuseful in cases of viral infection. As anti-ILT3 binding molecules actto enhance immune responses, they would be therapeutically useful insituations where more rapid or thorough clearance of pathogenic agents,e.g., bacteria and viruses would be beneficial.

As used herein, the term “viral infection” includes infections withorganisms including, but not limited to, HIV (e.g., HIV-1 and HIV-2),human herpes viruses, cytomegalovirus (esp. Human), Rotavirus,Epstein-Barr virus, Varicella Zoster Virus, hepatitis viruses, such ashepatitis B virus, hepatitis A virus, hepatitis C virus and hepatitis Evirus, paramyxoviruses: Respiratory Syncytial virus, parainfluenzavirus, measles virus, mumps virus, human papilloma viruses (for exampleHPV6, 11, 16, 18 and the like), flaviviruses (e.g. Yellow Fever Virus,Dengue Virus, Tick-borne encephalitis virus, Japanese EncephalitisVirus) or influenza virus.

As used herein, the term “bacterial infections” include infections witha variety of bacterial organisms, including gram-positive andgram-negative bacteria. Examples include, but are not limited to,Neisseria spp, including N. gonorrhea and N. meningitidis, Streptococcusspp, including S. pneumoniae, S. pyogenes, S. agalactiae, S. mutans;Haemophilus spp, including H. influenzae type B, non typeable H.influenzae, H. ducreyi; Moraxella spp, including M catarrhalis, alsoknown as Branhamella catarrhalis; Bordetella spp, including B.pertussis, B. parapertussis and B. bronchiseptica; Mycobacterium spp.,including M. tuberculosis, M. bovis, M. leprae, M. avium, M.paratuberculosis, M. smegmatis; Legionella spp, including L.pneumophila; Escherichia spp, including enterotoxic E. coli,enterohemorragic E. coli, enteropathogenic E. coli; Vibrio spp,including V. cholera, Shigella spp, including S. sonnei, S. dysenteriae,S. flexnerii; Yersinia spp, including Y. enterocolitica, Y. pestis, Y.pseudotuberculosis, Campylobacter spp, including C. jejuni and C. coli;Salmonella spp, including S. typhi, S. paratyphi, S. choleraesuis, S.enteritidis; Listeria spp., including L. monocytogenes; Helicobacterspp, including H. pylori; Pseudomonas spp, including P. aeruginosa,Staphylococcus spp., including S. aureus, S. epidermidis; Enterococcusspp., including E. faecalis, E. faecium; Clostridium spp., including C.tetani, C. botulinum, C. difficile; Bacillus spp., including B.anthracis; Corynebacterium spp., including C. diphtheriae; Borreliaspp., including B. burgdorferi, B. garinii, B. afzelii, B. andersonii,B. hermsii; Ehrlichia spp., including E. equi and the agent of the HumanGranulocytic Ehrlichiosis; Rickettsia spp, including R. rickettsii;Chlamydia spp., including C. trachomatis, C. neumoniae, C. psittaci;Leptsira spp., including L. interrogans; Treponema spp., including T.pallidum, T. denticola, T. hyodysenteriae. Preferred bacteria include,but are not limited to, Listeria, mycobacteria, mycobacteria (e.g.,tuberculosis), Anthrax, Salmonella and Listeria monocytogenes.

In another embodiment, T cells can be removed from a patient, andcontacted in vitro with an anti-ILT3 binding molecule, optionally withan activating signal (e.g., antigen plus APCs or a polyclonal antibody)and reintroduced into the patient.

Anti- ILT3 binding molecules may also be used prophylactically invaccines against various pathogens. Immunity against a pathogen, e.g., avirus, could be induced by vaccinating with a viral protein along withan ILT3 binding molecule (as described above). Alternately, anexpression vector which encodes genes for both a pathogenic antigen andan ILT3 binding molecule, e.g., a vaccinia virus expression vectorengineered to express a nucleic acid encoding a viral protein and anucleic acid encoding an ILT3 binding molecule, can be used forvaccination. Pathogens for which vaccines may be useful include, forexample, hepatitis B, hepatitis C, Epstein-Barr virus, cytomegalovirus,HIV-1, HIV-2, tuberculosis, malaria and schistosomiasis.

The present invention further encompasses binding molecules conjugatedto a diagnostic or therapeutic agent. The binding molecules can be useddiagnostically to, for example, monitor the development or progressionof a tumor as part of a clinical testing procedure to, e.g., determinethe efficacy of a given treatment regimen. Detection can be facilitatedby coupling the antibody to a detectable substance. Examples ofdetectable substances include various enzymes, prosthetic groups,fluorescent materials, luminescent materials, bioluminescent materials,radioactive materials, positron emitting metals using various positronemission tomographies, and nonradioactive paramagnetic metal ions. Thedetectable substance may be coupled or conjugated either directly to thebinding molecule or indirectly, through an intermediate (such as, forexample, a linker known in the art) using techniques known in the art.See, for example, U.S. Pat. No. 4,741,900 for metal ions which can beconjugated to binding molecules for use as diagnostics according to thepresent invention. Examples of suitable enzymes include horseradishperoxidase, alkaline phosphatase, beta-galactosidase, oracetylcholinesterase; examples of suitable prosthetic group complexesinclude streptavidin/biotin and avidin/biotin; examples of suitablefluorescent materials include umbelliferone, fluorescein, fluoresceinisothiocyanate, rhodamine, dichlorotriazinylamine fluorescein, dansylchloride or phycoerythrin; an example of a luminescent material includesluminol; examples of bioluminescent materials include luciferase,luciferin, and aequorin; and examples of suitable radioactive materialI¹²⁵ I¹³¹, I¹¹¹, In^(99 Tc).

Further, a binding molecule may be conjugated to a therapeutic moietysuch as a cytotoxin, e.g., a cytostatic or cytocidal agent, atherapeutic agent or a radioactive metal ion, e.g., alpha-emitters suchas, for example, ²¹³Bi. A cytotoxin or cytotoxic agent includes anyagent that is detrimental to cells. Examples include paclitaxol,cytochalasin B, gramicidin D, ethidium bromide, emetine, mitomycin,etoposide, tenoposide, vincristine, vinblastine, colchicin, doxorubicin,daunorubicin, dihydroxy anthracin dione, mitoxantrone, mithramycin,actinomycin D, 1-dehydrotestosterone, glucocorticoids, procaine,tetracaine, lidocaine, propranolol, and puromycin and analogs orhomologs thereof. Therapeutic agents include, but are not limited to,antimetabolites (e.g., methotrexate, 6-mercaptopurine, 6-thioguanine,cytarabine, 5-fluorouracil decarbazine), alkylating agents (e.g.,mechlorethamine, thioepa chlorambucil, melphalan, carnustine (BSNU) andlomustine (CCNU), cyclothosphamide, busulfan, dibromomannitol,streptozotocin, mitomycin C, and cis-dichlorodiamine platinum (II) (DDP)cisplatin), anthracyclines (e.g., daunorubicin (formerly daunomycin) anddoxorubicin), antibiotics (e.g., dactinomycin (formerly actinomycin),bleomycin, mithramycin, and anthramycin (AMC)), and anti-mitotic agents(e.g., vincristine and vinblastine).

The present invention is further directed to binding molecule-basedtherapies which involve administering binding molecules of the inventionto an animal, preferably a mammal, and most preferably a human, patientfor treating, detecting, and/or preventing one or more of the discloseddiseases, disorders, or conditions. Therapeutic compounds of theinvention include, but are not limited to, binding molecules of theinvention (including analogs and derivatives thereof as describedherein) and anti-idiotypic binding molecules as described herein. Thebinding molecules of the invention can be used to treat, diagnose,inhibit or prevent diseases, disorders or conditions associated withaberrant activity of ILT3, including, but not limited to, any one ormore of the diseases, disorders, or conditions described herein (e.g.,binding molecules of the invention may be provided in pharmaceuticallyacceptable compositions as known in the art or as described herein.

The binding molecules of this invention may be advantageously utilizedin combination with other monoclonal or chimeric binding molecules, orwith lymphokines or hematopoietic growth factors (such as, e.g., IL-2,IL-3 and IL-7), for example, which serve to increase the number oractivity of effector cells which interact with the binding molecules.

The binding molecules of the invention may be administered alone or incombination with other types of treatments, e.g., immunostimulatorytreatments or treatments designed to control the proliferation of atarget of activated immune cells (e.g., cancer cells or pathogens).Exemplary therapies include e.g., radiation therapy, chemotherapy,hormonal therapy, immunotherapy and anti-tumor agents, antibiotics, andimmunoglobulin. Generally, administration of products of a speciesorigin or species reactivity (in the case of binding molecules) that isthe same species as that of the patient is preferred. Thus, in apreferred embodiment, human binding molecules, derivatives, analogs, ornucleic acids, are administered to a human patient for therapy orprophylaxis.

A binding molecule of the invention can be administered to a humansubject for therapeutic purposes. Moreover, a binding molecule of theinvention can be administered to a non-human mammal expressing ILT3 withwhich the binding molecule cross-reacts (e.g., a primate) for veterinarypurposes or as an animal model of human disease. Regarding the latter,such animal models may be useful for evaluating the therapeutic efficacyof binding molecules of the invention (e.g., testing of dosages and timecourses of administration).

The present invention is further directed to binding molecule-basedtherapies which involve administering binding molecules of the inventionto an animal, preferably a mammal, and most preferably a human, patientfor treating, detecting, and/or preventing one or more of the discloseddiseases, disorders, or conditions. Therapeutic compounds of theinvention include, but are not limited to, binding molecules of theinvention (including analogs and derivatives thereof as describedherein) and anti-idiotypic binding molecules as described herein. Thebinding molecules of the invention can be used to treat, diagnose,inhibit or prevent diseases, disorders or conditions associated withaberrant activity of ILT3, including, but not limited to, any one ormore of the diseases, disorders, or conditions described herein (e.g.,binding molecules of the invention may be provided in pharmaceuticallyacceptable compositions as known in the art or as described herein).

VI. Pharmaceutical Compositions

The binding molecules of the invention can be incorporated intopharmaceutical compositions suitable for administration to a subject.Typically, the pharmaceutical composition comprises a binding moleculeof the invention and a pharmaceutically acceptable carrier. As usedherein the language “pharmaceutically acceptable carrier” is intended toinclude any and all solvents, dispersion media, coatings, antibacterialand antifungal agents, isotonic and absorption delaying agents, and thelike, compatible with pharmaceutical administration. The use of suchmedia and agents for pharmaceutically active substances is well known inthe art. Except insofar as any conventional media or agent isincompatible with the active compound, use thereof in the compositionsis contemplated. Supplementary active compounds can also be incorporatedinto the compositions.

A pharmaceutical composition of the invention is formulated to becompatible with its intended route of administration. Examples of routesof administration include parenteral, e.g., intravenous, intradermal,subcutaneous, oral (e.g., inhalation), transdermal (topical),transmucosal, and rectal administration. Solutions or suspensions usedfor parenteral, intradermal, or subcutaneous application can include thefollowing components: a sterile diluent such as water for injection,saline solution, fixed oils, polyethylene glycols, glycerine, propyleneglycol or other synthetic solvents; antibacterial agents such as benzylalcohol or methyl parabens; antioxidants such as ascorbic acid or sodiumbisulfite; chelating agents such as ethylenediaminetetraacetic acid;buffers such as acetates, citrates or phosphates and agents for theadjustment of tonicity such as sodium chloride or dextrose. pH can beadjusted with acids or bases, such as hydrochloric acid or sodiumhydroxide. The parenteral preparation can be enclosed in ampules,disposable syringes or multiple dose vials made of glass or plastic.

Pharmaceutical compositions suitable for injectable use include sterileaqueous solutions (where water soluble) or dispersions and sterilepowders for the extemporaneous preparation of sterile injectablesolutions or dispersion. For intravenous administration, suitablecarriers include physiological saline, bacteriostatic water, CremophorEL™ (BASF, Parsippany, N.J.) or phosphate buffered saline (PBS). In allcases, the composition must be sterile and should be fluid to the extentthat easy syringeability exists. It must be stable under the conditionsof manufacture and storage and must be preserved against thecontaminating action of microorganisms such as bacteria and fungi. Thecarrier can be a solvent or dispersion medium containing, for example,water, ethanol, polyol (for example, glycerol, propylene glycol, andliquid polyetheylene glycol, and the like), and suitable mixturesthereof. The proper fluidity can be maintained, for example, by the useof a coating such as lecithin, by the maintenance of the requiredparticle size in the case of dispersion and by the use of surfactants.Prevention of the action of microorganisms can be achieved by variousantibacterial and antifungal agents, for example, parabens,chlorobutanol, phenol, ascorbic acid, thimerosal, and the like. In manycases, it is preferable to include isotonic agents, for example, sugars,polyalcohols such as manitol, sorbitol, and sodium chloride in thecomposition. Prolonged absorption of the injectable compositions can bebrought about by including in the composition an agent which delaysabsorption, for example, aluminum monostearate and gelatin.

Sterile injectable solutions can be prepared by incorporating the activecompound in the required amount in an appropriate solvent with one or acombination of ingredients enumerated above, as required, followed byfiltered sterilization. Generally, dispersions are prepared byincorporating the active compound into a sterile vehicle which containsa basic dispersion medium and the required other ingredients from thoseenumerated above. In the case of sterile powders for the preparation ofsterile injectable solutions, the preferred methods of preparation arevacuum drying and freeze-drying which yields a powder of the activeingredient plus any additional desired ingredient from a previouslysterile-filtered solution thereof.

Oral compositions generally include an inert diluent or an ediblecarrier. They can be enclosed in gelatin capsules or compressed intotablets. For the purpose of oral therapeutic administration, the activecompound can be incorporated with excipients and used in the form oftablets, troches, or capsules. Oral compositions can also be preparedusing a fluid carrier for use as a mouthwash, wherein the compound inthe fluid carrier is applied orally and swished and expectorated orswallowed. Pharmaceutically compatible binding agents, and/or adjuvantmaterials can be included as part of the composition. The tablets,pills, capsules, troches and the like can contain any of the followingingredients, or compounds of a similar nature: a binder such asmicrocrystalline cellulose, gum tragacanth or gelatin; an excipient suchas starch or lactose, a disintegrating agent such as alginic acid,Primogel, or corn starch; a lubricant such as magnesium stearate orSterotes; a glidant such as colloidal silicon dioxide; a sweeteningagent such as sucrose or saccharin; or a flavoring agent such aspeppermint, methyl salicylate, or orange flavoring.

For administration by inhalation, the compounds are delivered in theform of an aerosol spray from pressured container or dispenser whichcontains a suitable propellant, e.g., a gas such as carbon dioxide, or anebulizer.

Systemic administration can also be by transmucosal or transdermalmeans. For transmucosal or transdermal administration, penetrantsappropriate to the barrier to be permeated are used in the formulation.Such penetrants are generally known in the art, and include, forexample, for transmucosal administration, detergents, bile salts, andfusidic acid derivatives. Transmucosal administration can beaccomplished through the use of nasal sprays or suppositories. Fortransdermal administration, the active compounds are formulated intoointments, salves, gels, or creams as generally known in the art.

The compounds can also be prepared in the form of suppositories (e.g.,with conventional suppository bases such as cocoa butter and otherglycerides) or retention enemas for rectal delivery.

In one embodiment, the binding molecules of the invention are preparedwith carriers that will protect the compound against rapid eliminationfrom the body, such as a controlled release formulation, includingimplants and microencapsulated delivery systems. Biodegradable,biocompatible polymers can be used, such as ethylene vinyl acetate,polyanhydrides, polyglycolic acid, collagen, polyorthoesters, andpolylactic acid. Methods for preparation of such formulations should beapparent to those skilled in the art. The materials can also be obtainedcommercially from Alza Corporation and Nova Pharmaceuticals, Inc.Liposomal suspensions can also be used as pharmaceutically acceptablecarriers. These can be prepared according to methods known to thoseskilled in the art, for example, as described in U.S. Pat. No.4,522,811.

It is especially advantageous to formulate oral or parenteralcompositions in dosage unit form for ease of administration anduniformity of dosage. Dosage unit form as used herein refers tophysically discrete units suited as unitary dosages for the subject tobe treated; each unit containing a predetermined quantity of activecompound calculated to produce the desired therapeutic effect inassociation with the required pharmaceutical carrier. The specificationfor the dosage unit forms of the invention are dictated by and directlydependent on the unique characteristics of the active compound and theparticular therapeutic effect to be achieved, and the limitationsinherent in the art of compounding such an active compound for thetreatment of individuals.

Toxicity and therapeutic efficacy of such compounds can be determined bystandard pharmaceutical procedures in cell cultures or experimentalanimals, e.g., for determining the LD50 (the dose lethal to 50% of thepopulation) and the ED50 (the dose therapeutically effective in 50% ofthe population). The dose ratio between toxic and therapeutic effects isthe therapeutic index and it can be expressed as the ratio LD50/ED50.Compounds which exhibit large therapeutic indices are preferred. Whilecompounds that exhibit toxic side effects can be used, care should betaken to design a delivery system that targets such compounds to thesite of affected tissue in order to minimize potential damage touninfected cells and, thereby, reduce side effects.

The data obtained from the cell culture assays and animal studies can beused in formulating a range of dosage for use in humans. The dosage ofsuch compounds lies preferably within a range of circulatingconcentrations that include the ED50 with little or no toxicity. Thedosage may vary within this range depending upon the dosage formemployed and the route of administration utilized. For any compound usedin the method of the invention, the therapeutically effective dose canbe estimated initially from cell culture assays. A dose can beformulated in animal models to achieve a circulating plasmaconcentration range that includes the IC50 (i.e., the concentration ofthe test compound which achieves a half-maximal inhibition of symptoms)as determined in cell culture. Such information can be used to moreaccurately determine useful doses in humans. Levels in plasma can bemeasured, for example, by high performance liquid chromatography.

The pharmaceutical compositions can be included in a container, pack, ordispenser together with instructions for administration.

VII. Administration of Binding Molecules of the Invention

Binding molecules of the invention are administered to subjects in abiologically compatible form suitable for pharmaceutical administrationin vivo. By “biologically compatible form suitable for administration invivo” is meant a form of the agent to be administered in which any toxiceffects are outweighed by the therapeutic effects of the bindingmolecule.

Administration of a therapeutically active amount of the therapeuticcompositions of the present invention is defined as an amount effective,at dosages and for periods of time necessary to achieve the desiredresult. For example, a therapeutically active amount of binding moleculemay vary according to factors such as the disease state, age, sex, andweight of the individual, and the ability of the binding molecule toelicit a desired response in the individual. Dosage regimens can beadjusted to provide the optimum therapeutic response. For example,several divided doses can be administered daily or the dose can beproportionally reduced as indicated by the exigencies of the therapeuticsituation.

The pharmaceutical compositions of the invention may include a“therapeutically effective amount” or a “prophylactically effectiveamount” of a binding molecule of the invention. A “therapeuticallyeffective amount” refers to an amount effective, at dosages and forperiods of time necessary, to achieve the desired therapeutic result. Atherapeutically effective amount of the binding molecule may varyaccording to factors such as the disease state, age, sex, and weight ofthe individual, and the ability of the binding molecule to elicit adesired response in the individual. A therapeutically effective amountis also one in which any toxic or detrimental effects of the bindingmolecule are outweighed by the therapeutically beneficial effects. A“prophylactically effective amount” refers to an amount effective, atdosages and for periods of time necessary, to achieve the desiredprophylactic result. Typically, since a prophylactic dose is used insubjects prior to or at an earlier stage of disease, theprophylactically effective amount will be less than the therapeuticallyeffective amount.

Dosage regimens may be adjusted to provide the optimum desired response(e.g., a therapeutic or prophylactic response). For example, a singlebolus may be administered, several divided doses may be administeredover time or the dose may be proportionally reduced or increased asindicated by the exigencies of the therapeutic situation. It isespecially advantageous to formulate parenteral compositions in dosageunit form for ease of administration and uniformity of dosage. Dosageunit form as used herein refers to physically discrete units suited asunitary dosages for the mammalian subjects to be treated; each unitcontaining a predetermined quantity of active compound calculated toproduce the desired therapeutic effect in association with the requiredpharmaceutical carrier. The specification for the dosage unit forms ofthe invention are dictated by and directly dependent on (a) the uniquecharacteristics of the active compound and the particular therapeutic orprophylactic effect to be achieved, and (b) the limitations inherent inthe art of compounding such an active compound for the treatment ofsensitivity in individuals.

An exemplary, non-limiting range for a therapeutically orprophylactically effective amount of a binding molecule of the inventionis, e.g., from about 0.1-25 mg/kg, from about 1.0-10 mg/kg, from about0.5-2.5 mg/kg, from about 5-25 mg/kg, from about 1-400 mg/kg. It is tobe noted that dosage values may vary with the type and severity of thecondition to be alleviated. It is to be further understood that for anyparticular subject, specific dosage regimens should be adjusted overtime according to the individual need and the professional judgment ofthe person administering or supervising the administration of thecompositions, and that dosage ranges set forth herein are exemplary onlyand are not intended to limit the scope or practice of the claimedcomposition. Additional, non-limiting ranges for a therapeutically orprophylactically effective amount of a binding molecule of the inventionis from about 0.0001 to 100 mg/kg, and from about 0.01 to 5 mg/kg (e.g.,0.02 mg/kg, 0.25 mg/kg, 0.5 mg/kg, 0.75 mg/kg, 1 mg/kg, 2 mg/kg, etc.),of the subject body weight. For example, dosages can be 1 mg/kg bodyweight or 10 mg/kg body weight or within the range of 1-10 mg/kg,preferably at least 1 mg/kg. Doses intermediate in the above ranges arealso intended to be within the scope of the invention.

Subjects can be administered such doses daily, on alternative days,weekly or according to any other schedule determined by empiricalanalysis. An exemplary treatment entails administration in multipledosages over a prolonged period, for example, of at least six months.Additional exemplary treatment regimes entail administration once perevery two weeks or once a month or once every 3 to 6 months. Exemplarydosage schedules include 1-10 mg/kg or 15 mg/kg on consecutive days, 30mg/kg on alternate days or 60 mg/kg weekly.

Binding molecules of the invention can be administered on multipleoccasions. Intervals between single dosages can be, e.g., daily, weekly,monthly or yearly. Intervals can also be irregular as indicated bymeasuring blood levels of binding molecule in the patient.

Binding molecules of the invention can optionally be administered incombination with other agents that are effective in treating thedisorder or condition in need of treatment (e.g., prophylactic ortherapeutic). Preferred additional agents are those which are artrecognized and are standardly administered for a particular disorder.

The binding molecule can be administered in a convenient manner such asby injection (subcutaneous, intravenous, etc.), oral administration,inhalation, transdermal application, or rectal administration. Dependingon the route of administration, the active compound can be coated in amaterial to protect the compound from the action of enzymes, acids andother natural conditions which may inactivate the compound. For example,to administer the agent by other than parenteral administration, it maybe desirable to coat, or co-administer the agent with, a material toprevent its inactivation.

A binding molecule of the present invention can be administered by avariety of methods known in the art, although for many therapeuticapplications, the preferred route/mode of administration is intravenousinjection or infusion. As will be appreciated by the skilled artisan,the route and/or mode of administration will vary depending upon thedesired results. In certain embodiments, the active compound may beprepared with a carrier that will protect the compound against rapidrelease, such as a controlled release formulation, including implants,transdermal patches, and microencapsulated delivery systems.Biodegradable, biocompatible polymers can be used, such as ethylenevinyl acetate, polyanhydrides, polyglycolic acid, collagen,polyorthoesters, and polylactic acid. Many methods for the preparationof such formulations are patented or generally known to those skilled inthe art. See, e.g., Sustained and Controlled Release Drug DeliverySystems, J. R. Robinson, ed., Marcel Dekker, Inc., New York, 1978.

In certain embodiments, a binding molecule of the invention may beorally administered, for example, with an inert diluent or anassimilable edible carrier. The compound (and other ingredients, ifdesired) may also be enclosed in a hard or soft shell gelatin capsule,compressed into tablets, or incorporated directly into the subject'sdiet. For oral therapeutic administration, the compounds may beincorporated with excipients and used in the form of ingestible tablets,buccal tablets, troches, capsules, elixirs, suspensions, syrups, wafers,and the like. To administer a compound of the invention by other thanparenteral administration, it may be necessary to coat the compoundwith, or co-administer the compound with, a material to prevent itsinactivation.

Binding molecules can be co-administered with enzyme inhibitors or in anappropriate carrier such as liposomes. Pharmaceutically acceptablediluents include saline and aqueous buffer solutions. Adjuvant is usedin its broadest sense and includes any immune stimulating compound suchas interferon. Adjuvants contemplated herein include resorcinols,non-ionic surfactants such as polyoxyethylene oleyl ether andn-hexadecyl polyethylene ether. Enzyme inhibitors include pancreatictrypsin inhibitor, diisopropylfluorophosphate (DEEP) and trasylol.Liposomes include water-in-oil-in-water emulsions as well asconventional liposomes (Sterna et al. (1984) J. Neuroimmunol. 7:27).

The active compound may also be administered parenterally orintraperitoneally. Dispersions can also be prepared in glycerol, liquidpolyethylene glycols, and mixtures thereof and in oils. Under ordinaryconditions of storage and use, these preparations may contain apreservative to prevent the growth of microorganisms.

When the active compound is suitably protected, as described above, thebinding molecule can be orally administered, for example, with an inertdiluent or an assimilable edible carrier.

Supplementary active compounds can also be incorporated into thecompositions. In certain embodiments, a binding molecule of theinvention is coformulated with and/or coadministered with one or moreadditional therapeutic agents. For example, an anti-ILT3 bindingmolecule of the invention may be coformulated and/or coadministered withone or more additional antibodies that bind other targets e.g.,antibodies that bind other cytokines or that bind cell surfacemolecules. Such combination therapies may advantageously utilize lowerdosages of the administered therapeutic agents, thus avoiding possibletoxicities or complications associated with the various monotherapies.

The present invention further encompasses binding molecules conjugatedto a diagnostic or therapeutic agent. A binding molecule can be useddiagnostically to, for example, monitor the development or progressionof a tumor as part of a clinical testing procedure to, e.g., determinethe efficacy of a given treatment regimen. Detection can be facilitatedby coupling the antibody to a detectable substance. Examples ofdetectable substances include various enzymes, prosthetic groups,fluorescent materials, luminescent materials, bioluminescent materials,radioactive materials, positron emitting metals using various positronemission tomographies, and nonradioactive paramagnetic metal ions. Thedetectable substance may be coupled or conjugated either directly to thebinding molecule or indirectly, through an intermediate (such as, forexample, a linker known in the art) using techniques known in the art.See, for example, U.S. Pat. No. 4,741,900 for metal ions which can beconjugated to binding molecules for use as diagnostics according to thepresent invention. Examples of suitable enzymes include horseradishperoxidase, alkaline phosphatase, beta-galactosidase, oracetylcholinesterase; examples of suitable prosthetic group complexesinclude streptavidin/biotin and avidin/biotin; examples of suitablefluorescent materials include umbelliferone, fluorescein, fluoresceinisothiocyanate, rhodamine, dichlorotriazinylamine fluorescein, dansylchloride or phycoerythrin; an example of a luminescent material includesluminol; examples of bioluminescent materials include luciferase,luciferin, and aequorin; and examples of suitable radioactive materialI¹²⁵ I¹³¹, I¹¹¹, In^(99 Tc).

Further, a binding molecule may be conjugated to a therapeutic moietysuch as a cytotoxin, e.g., a cytostatic or cytocidal agent, atherapeutic agent, a radioactive metal ion, e.g., alpha-emitters suchas, for example, ²¹³Bi, biological toxins, prodrugs, peptides, proteins,enzymes, viruses, lipids, biological response modifiers, pharmaceuticalagents, immunologically active ligands (e.g., lymphokines or otherantibodies). In another embodiment, a binding molecule of the inventioncan be conjugated to a molecule that decreases vascularization oftumors. In other embodiments, the disclosed compositions may comprisebinding molecules of the invention coupled to drugs or prodrugs. Stillother embodiments of the present invention comprise the use of bindingmolecules of the invention conjugated to specific biotoxins or theircytotoxic fragments such as ricin, gelonin, pseudomonas exotoxin ordiphtheria toxin. The selection of which conjugated or unconjugatedbinding molecule to use will depend on the type and stage of cancer, useof adjunct treatment (e.g., chemotherapy or external radiation) andpatient condition. It will be appreciated that one skilled in the artcould readily make such a selection in view of the teachings herein.

A cytotoxin or cytotoxic agent includes any agent that is detrimental tocells. Examples include paclitaxol, cytochalasin B, gramicidin D,ethidium bromide, emetine, mitomycin, etoposide, tenoposide,vincristine, vinblastine, colchicin, doxorubicin, daunorubicin,dihydroxy anthracin dione, mitoxantrone, mithramycin, actinomycin D,1-dehydrotestosterone, glucocorticoids, procaine, tetracaine, lidocaine,propranolol, and puromycin and analogs or homologs thereof. Therapeuticagents include, but are not limited to, antimetabolites (e.g.,methotrexate, 6-mercaptopurine, 6-thioguanine, cytarabine,5-fluorouracil decarbazine), alkylating agents (e.g., mechlorethamine,thioepa chlorambucil, melphalan, carmustine (BSNU) and lomustine (CCNU),cyclothosphamide, busulfan, dibromomannitol, streptozotocin, mitomycinC, and cis-dichlorodiamine platinum (II) (DDP) cisplatin),anthracyclines (e.g., daunorubicin (formerly daunomycin) anddoxorubicin), antibiotics (e.g., dactinomycin (formerly actinomycin),bleomycin, mithramycin, and anthramycin (AMC)), and anti-mitotic agents(e.g., vincristine and vinblastine).

This invention is further illustrated by the following examples, whichshould not be construed as limiting. The contents of all references,patents and published patent applications cited throughout thisapplication, as well as the Figures, are incorporated herein byreference.

EXAMPLES Example 1 Isolation and Purification of 9B11

The gene encoding ILT3 was cloned and used to immunize mice forgeneration of anti-ILT3 monoclonal antibodies. The 9B11 antibody is anIgG1 antibody.

The 9B11 antibody was purified as follows:

-   -   1. Washed 20 ml Protein G (Pharmacia HR 10/30) with 5 CV of dPBS    -   2. Loaded 1 L (run 1) or 2 L (run 2) of mouse anti-human ILT3        supernatant    -   3. Washed with 10 CV of dPBS    -   4. Eluted with 100 mM Citrate, pH 2.8 directly into 1 M Tris        (20-25% v:v)    -   5. Stripped with 100 mM Citrate, pH 2.8, 0.3 M NaCl        The 9B11 antibody was shown to cross-react to cynomolgus monkey        and baboon monocytes.

Example 2 Dendritic Cells Treated In Vitro With 9B11 Have LowerExpression of Cell Surface Co-Stimulatory Molecules

MDDC were derived in the presence of either IL-10 or anti-ILT3 mAbs(5A1, 9B11, or 9G3). Immature and mature dendritic cells were used ascontrols. In addition MDDC were also derived in the presence of TRX1 asa negative control. The results are shown in FIG. 1 which demonstratesthat MDDC differentiated in the presence of 9B11 have lower expressionof cell surface co-stimulatory molecules, such as CD86, CD80, CD83 andHLA-DR as measured by flow cytometry.

As shown above, cells that are differentiated in the presence of 9B11demonstrate a decreased cell surface expression pattern of costimulatorymolecules. Therefore, it is likely that these cells will be unable togenerate an allogenic response of T cells in a mixed lymphocytereaction. As shown in FIG. 2, MDDCs differentiated in the presence of9B11 result in anergic T cell stimulation in a mixed lymphocytereaction. DCs were added at either 500 or 1000 cells to 2×10⁵ T cells.The cells were stimulated for 3 days prior to the addition of³H-thymidine.

Furthermore, MDDCs derived in the presence of 9B11 are unable to produceIL-12, TNF-α or IL-1α when stimulated with LPS. Monocytes were treatedwith GM-CSF and IL-4 on days 0 and 3. IL-10 or ILT3 (9B11; 10 μg/ml) wasadded on day 0 and 3. On day 5 cells were washed and LPS (5 μg/ml) andwere added to the mature cultures. Supernatant fluid was harvested 48hours after the addition of LPS. Cytokines were measured by ELISA(Pierce Endogen). Two different monocyte donors were used (donor #26 anddonor #5) (FIG. 3).

Freshly isolated blood dendritic cells incubated with 9B11 were unableto fully upregulate the expression of co-stimulatory molecules when acocktail of cytokines (IL-6, IL-1 beta, TNF-alpha, and PGE) was used tomature the cells. Freshly isolated blood dendritic cells were incubatedwith 9B11 24 hours prior to the addition of the maturation cocktail. Thecells were phenotyped 48 hours later to determine if treatment with 9B11results in decreased expression of co-stimulatory molecules. As shown inFIG. 4, treatment of monocytes with 9B11 resulted in decreasedexpression of both CD86 and HLA-DR.

9B11 also inhibits Ca⁺² flux in monocytes induced by the activatingimmunoreceptor tyrosine-based activation motif (ITAM), CD32. Monocyteswere treated with anti-CD32 followed by a goat anti-mouse IgG, IgM tocross-link, which will result in significant Ca+2 flux. However,incubation with 9B11 prior to the addition of CD32 and cross-linkingresulted in decreased Ca+2 flux by these monocytes. This was specificfor the ILT3 antibodies as an isotype control (mouse IgG1) resulted inless inhibition of Ca+2 flux (FIG. 5).

Intracellular calcium flux studies using flow cytometry analysis wasperformed as described by Rabin, et al. (J. Immunol.(1999)162:3840-3850). Briefly, monocyte-derived dendritic cells (2×10⁷)were suspended in HBSS-HEPES (HBSS supplemented with 10 mM HEPES, Ca⁺⁺,Mg⁺⁺, and 1% fetal calf serum). Indo-1 and pleuronic detergent(Molecular Probes, Eugene, Oreg.) were added at final concentrations of5 μM and 300 μg/mL, respectively. The cell suspension was incubated at30° C. for 45 minutes with gentle agitation. Cells were then washedtwice with the HBSS-HEPES, stained with anti-CD1a, and washed again.Calcium flux for CD1a⁺ dendritic cells was performed using a FACSVantageflow cytometer (Becton Dickinson) equipped with an argon laser tuned to488 nM and a krypton laser tuned to 360 nM. Indo-1 fluorescence wasanalyzed at 390/20 nM and 530/20 nM for bound and free calcium,respectively. Before stimulation, cell suspensions were warmed at 37° C.for 3 minutes. The CD1a⁺ cell population was gated, and baselinefluorescent ratios were collected for 30 seconds. Cells were thenstimulated with either fMLP (10⁵ M), T-20 peptide (10⁵ M), or F-peptide(10 ⁵ M) followed by fMLP (10⁸ M). Collections continued until calciumflux returned to basal levels. Changes in Indo-1 fluorescence wereexpressed as the ratio of bound to free intracellular calcium, andscattergrams represented the entire CD1a⁺ cell population at the time ofstimulation. Data analysis was performed using Flowjo software (TreeStar, San Carlos, Calif.).

Example 3 Dendritic Cells Treated In Vitro With 9B11 Have HigherExpression of Cell Surface Inhibitory Receptors

9B11 was also shown to upmodulate the expression of inhibitoryreceptors, e.g., receptors that generate a negative inhibitory in acell. Monocytes were isolated using magnetic bead separation technology.The monocytes were treated every other day with 9B11, GM-CSF and IL4. Onday 5, a portion of these cells were matured using IL1b, IL6, TNFα, andPGE2. Cells were incubated for a further seven days and then RNA wasprepared from immature dendritic cells (iDC) (cells not treated withIL1b, IL6, TNFα, and PGE2) and mature dendritic cells (mDC). The RNA wasused to generate cDNA for QPCR. The data is expressed relative to thehousekeeping gene 18sRNA. A mouse IgG1 was used as an isotype controland both antibodies were used at a concentration of 10 μg/ml.

The results show that the culturing of monocytes such that they developinto dendritic cells in the presence of an ILT3 binding molecule causessome inhibitory molecules to upregulate. IDO (indolamine) is extremelyoverexpressed in ILT3 binding molecule treated cells. This molecule isassociated with the generation of tolerance. Tolergenic dendritic cellshave also been shown to express CD200R and have been shown to betolergenic in vivo. CD200R and CD40L were also elevated in ILT3 bindingmolecule treated cells compared to isotype controls, and although 9B11treatment increased expression of FCGRIIb and FCGRIIa, all of thesamples had equal expression of FCGRIIa compared to FCGRIIb. The effectis specific to immature DC, as the expression of the same receptors onmature DC is no different from isotype control.

Example 4 In Vivo Characterization of 9B11

Rhesus macaques were immunized with 9B11 during the priming phase e.g.,at days −1, 0, and +1, of a vaccination protocol using Mycobacteriumtuberculosis as antigen. Subsequent challenge with antigen at day +18resulted in exacerbation of a cutaneous DTH response. These resultsindicate that 9B11 acts as an adjuvant useful in enhancing immuneresponses (e.g., in the case of infection and or malignancy) with lessassociated morbidity compared to existing adjuvants.

Example 7 Preparation of a Chimeric anti-ILT3 Binding Molecule

The 9B11 variable light chain region was grafted to a human light chainconstant region using conventional molecular biological techniques. TheIgG1 light chain constant region was used. The amino acid sequence ofthe complete chimeric light chain GITR binding molecule is shown below:

(SEQ ID NO: 25) DIVLTQSPATLSVTPGDSVSLSCRASQGLTNDLHWYQQKPHESPRLLIKYASQSISGIPSRFSGSGSGTDFTLTINSVETEDFGVFFCQQSNSWPFTFGAGTKLEIKRTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQG LSSPVTKSFNRGEC

The 9B11 variable heavy chain was also grafted to a human heavy chainconstant region using conventional molecular biological techniques. TheIgG1 heavy chain constant region was used. The amino acid sequence ofthe complete chimeric heavy chain ILT3 binding molecule is shown below(also referred to as “Gly”):

(SEQ ID NO: 26) EVKLVESGGDLVKPGGSLKLSCAASGFAFSSYDMSWVRQTPEKRLEWVATISSSGSYTYYPDSVKGRFTISRDNARNTLYLQMSSLRSEDTALYYCERLWGAMDYWGQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPICDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQY N STYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTICNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK.

Since the amino acid sequence NX(S/T) is a putative consensus sequencefor a glycosylation site which may affect the production of the bindingmolecule, and IgG1 constant region of the 9B11 heavy chain has thesequence NST, a second version of the heavy chain constant region wasprepared to conservatively substitute a glutamine for an asparagine atamino acid residue 296 (bolded and underlined above) of SEQ ID NO:27.Accordingly, a second human constant region was grafted to the 9B11heavy chain variable region. The amino acid sequence of the completechimeric heavy chain ILT3 binding molecule is shown below (also referredto as “Agly”):

(SEQ ID NO: 27) EVKLVESGGDLVKPGGSLKLSCAASGFAFSSYDMSWVRQTPEKRLEWVATISSSGSYTYYPDSVKGRFTISRDNARNTLYLQMSSLRSEDTALYYCERLWGAMDYWGQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQY A STYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTICNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK.

Example 8 Preparation of Humanized Forms of the 9B11 Anti-ILT3 BindingMolecule

The CDR homology based strategy described in Hwang et al. (2005) Methods(36) 35-42 was used to humanize 9B11. The heavy and light chain aminoacid sequences were blasted using a publicly available database, and theresults indicated that 9B11 had a 1-3 heavy chain canonical structureand a 2-1-1 light chain canonical structure. From this, all germ linekappa chain V genes with a 2-1-1 canonical structure in the IMGTdatabase were compared with the 9B11 antibody sequence. The same wasdone for the heavy chain where all 1-3 germ line heavy chain V geneswere compared to the 9B11 amino acid sequence. Only the CDR sequenceswere compared and the frameworks were selected based on which germlinesequences had the most matches in the CDRs. (see alignments below).

For the light chain, the 1-17*01 sequence had 15 matches in the CDRs andwas selected. The Jκ3 J gene segment sequence has the most matches,however, the Jκ2 J gene sequence (GQGTKLEIKR) (SEQ ID NO:19) may also beused.

Light Chain V Genes with 2-1-1 Canonical Structure IMGT Gene CDR1 CDR2CDR3 IDs Name IGKV1-6 RASQGIRNDLG...... AASSLSQ....... LQDYNYP.. 12IGKV1-9 RASQGISSYLA...... AASTLQS....... QQLNSYP.. 14 IGKV1-12RASQGISSWLA...... AASSLQS....... QQANSFP.. 14 IGKV1-16 RASQGISSWLA......AASSLQS....... QQYNSYP.. 14 IGKV1D-16 RARQGISSWLA...... AASSLQS.......QQYNSYP.. 13 IGKV1-17 RASQGIRNDLG...... AASSLQS....... LQHNSYP.. 15IGKV1-27 RASQGISNYLA...... AASTLQS....... QKYNSAP.. 14 IGKV1-39RASQSISSYLN...... AASSLQS....... QQSYSTP.. 13 IGKV1D-43WASQGISSYLA...... YASSLQS....... QQYYSTP.. 13 9B11 RASQGLTNDLH......YASQSIS....... QQSNSWP

All germ line light chain kappa chain V genes with a 2-1-1 canonicalstructure in the IMGT database were compared with the 9B11 antibodysequence. The same was done for the heavy chain where all 3-1 germ lineheavy chain V genes were compared to the 9B11 amino acid sequence

Using this methodology one version of the light chain can be made:

(SEQ ID NO: 28) DIQMTQSPSSLSASVGDRVTITCRASQGLTNDLHWYQQKPGKAPKRLIYYASQSISGVPSRFSGSGSGTEFTLTISSLQPEDFATYYCQQSNSWPFTFGQGTKLEIK (the CDRs are italicized)

A number of heavy chain germline sequences had 16 matches to the 9B11antibody, however, 3-21*01 was selected because the S at the start ofCDR 2 is most similar (conservative amino acid substitution) to the T inthe chimeric sequence. In addition, the framework of 3-21*01 ends withCAR as opposed to CAK or CARI in the other heavy chain germlinesequences with 16 matches.

For the J gene segment of the heavy chain, JH4 had the most matches andwas therefore, selected. The amino acid sequences are then reversetranslated and primers corresponding to the desired nucleotide sequenceare obtained from IDT (Coralville, Iowa).

Heavy Chain V Genes with 1-3 Canonical  Structures IMGT Gene Name CDR1CDR2 IDs IGHV3-11 DYYMS..... YISSSGSTIYYADSVKG 16 IGHV3-21 SYSMN.....SISSSSSYIYYADSVKG 16 IGHV3-23-1 SYAMS..... AISGSGGSTYYADSVKG 16IGHV3-23-2 SYAMS..... AISGSGGSTYYGDSVKG 16 IGHV3-48 SYSMN.....YISSSSSTIYYADSVKG 15 IGHV3-48-3 SYEMN..... YISSSGSTIYYADSVKG 16 9B11SYDMS..... TISSSGSYTYYPDSVKG

Using this methodology one version of the heavy chain can be made:

(SEQ ID NO: 29) EVQLVESGGGLVKPGGSLRLSCAASGFAFSSYDMSWVRQAPGKGLEWVSTISSSGSYTYYPDSVKGRFTISRDNAKNSLYLQMNSLRAEDTAVYYCARLW GAMDYWGQGTLVTVSS.

A CLUSTAL W (1.82) multiple sequence alignment (using a Blosum scoringmatrix with a gap penalty of 10) of the 9B11 light chain variable regionand the 1-17*01 germline light chain sequence was also performed. Theresults are presented below:

9B11 DIVLTQSPATLSVTPGDSVSLSCRASQGLTNDLHWYQQKP 1-17*01DIQMTQSPSSLSASVGDRVTITCRASQGIRNDLGWYQQKP** :****::**.: ** *:::******: *** ****** 9B11HESPRLLIKYASQSISGIPSRFSGSGSGTDFTLTINSVETEDFGVFFCQQSNSWPFTFGA 1-17*01GKAPKRLIYAASSLQSGVPSRFSGSGSGTEFTLTISSLQPEDFATYYCLQHNSYP----- ::*: **  **.  **:***********:*****.*::.***..::* * **:* 9B11 GTKLEIK1-17*01 -------

Based on the CLUSTAL W analyses, several amino acid residues in thehuman framework were identified for potential substitution with aminoacid residues corresponding to the 9B11 framework residues in thehumanized 9B11 light chain. Specifically, the Q at position 3, the M atposition 4, the S at position 9, the S at position 10, the A at position13, the S at position 14, the V at position 15, the Rat position 18, theT at position 20, the I at position 21, the Tat position 22, the G atposition 41, the K at position 42, the A at position 43, the K atposition 45, the R at position 46, the Y at position 49, the V atposition 58, the E at position 70, the S at position 76, the L atposition 78, the Q at position 79, the P at position 80, the A atposition 84, the T at position 85, the Y at position 86, the Y atposition 87, and the Q at position 100.

Similarly, a CLUSTAL W (1.82) multiple sequence alignment (using aBlosum scoring matrix with a gap penalty of 10) of the 9B11 heavy chainvariable region and the germline heavy chain proteins with a 3-21*01amino acid sequence was also performed. The results are presented below:

9B11 EVKLVESGGDLVKPGGSLKLSCAASGFAFSSYDMSWVRQTPEKRLEWVATISSSGSYTYY3-21-01 EVQLVESGGGLVKPGGSLRLSCAASGFTFSSYSMNWVRQAPGKGLEWVSSISSSSSYIYY**:******.********:********:****.*.****:* * ****::****.** ** 9B11PDSVKGRFTISRDNARNTLYLQMSSLRSEDTALYYCER 3-21-01ADSVKGRFTISRDNAKNSLYLQMNSLRAEDTAVYYCAR.**************:*:*****.***:****:*** *

Based on the CLUSTAL W analyses, several amino acid residues in thehuman framework were identified for potential substitution with aminoacid residues corresponding to the 9B11 framework residues in thehumanized 9B11 heavy chain.

Specifically, the Q at position 3, the G at position 10, the R atposition 19, the A at position 40, the G at position 42, the G atposition 44, the S at position 49, the K at position 76, the S atposition 78, the N at position 84, the A at position 88, the V atposition 93, and/or the A at position 97.

Based on the above, two humanized full-length 9B11 binding molecules canbe made having the following humanized heavy and light chaincombinations:

Full-length Version 1 (Hu9B11-Gly)—humanized (Hu) 9B11 Light chain(L)/humanized Heavy chain and comprising a constant region having an N(“Gly”)

Full-length Version 2 (Hu9B11-Agly)—humanized (Hu) 9B11 Light chain(L)/humanized Heavy chain and comprising a constant region having an A(“Agly”)

The amino acid sequence of the glycosylated IgG1 heavy chain constantregion that was used to make the full-length binding molecules is shownbelow:

(SEQ ID NO: 30) ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK.

The amino acid sequence of the aglycosylated IgG1 heavy chain constantregion that was used to make the full-length binding molecules is shownbelow:

(SEQ ID NO: 31) ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYASTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK.

The amino acid sequence of the IgG1 light chain constant region that wasused to make the full-length binding molecules is shown below:

(SEQ ID NO: 32) RTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTK SFNRGEC.

The complete amino acid sequence of the humanized 9B11 light chain isshown below:

(SEQ ID NO: 33) DIQMTQSPSSLSASVGDRVTITCRASQGLTNDLHWYQQKPGKAPKRLIYYASQSISGVPSRFSGSGSGTEFTLTISSLQPEDFATYYCQQSNSWPFTFGQGTKLEIKRTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQG LSSPVTKSFNRGEC.

The leader sequence set forth in SEQ ID NO:21 may optionally beincluded.

The complete amino acid sequences of the humanized 9B11 heavy chainversions Hu9B11-Gly and Hu9B11 -Agly are shown below:

Hu9B11-Gly (SEQ ID NO: 34)EVQLVESGGGLVKPGGSLRLSCAASGFAFSSYDMSWVRQAPGKGLEWVSTISSSGSYTYYPDSVKGRFTISRDNAKNSLYLQMNSLRAEDTAVYYCARLW GAMDYWGQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPICPKDTLMISRTPEVTCVVVDVSHEDPEVICFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGICEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK; and Hu9B11-Agly (SEQ ID NO: 35)EVQLVESGGGLVKPGGSLRLSCAASGFAFSSYDMSWVRQAPGKGLEWVSTISSSGSYTYYPDSVKGRFTISRDNAKNSLYLQMNSLRAEDTAVYYCARLW GAMDYWGQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHICPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYASTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK

The leader sequence set forth in SEQ ID NO:22 may optionally beincluded.

Equivalents

Those skilled in the art will recognize, or be able to ascertain usingno more than routine experimentation, many equivalents to the specificembodiments of the invention described herein. Such equivalents areintended to be encompassed by the following claims.

1-43. (canceled)
 44. An isolated antibody that specifically binds ILT3,or an antigen-binding fragment of the antibody, comprising: a heavychain variable region (VH) complementarity determining region 1 (VHCDR1) comprising the amino acid sequence shown in SEQ ID NO: 3; a heavychain variable region (VH) complementarity determining region 2 (VHCDR2) comprising the amino acid sequence shown in SEQ ID NO: 4; a heavychain variable region (VH) complementarity determining region 3 (VHCDR3) comprising the amino acid sequence shown in SEQ ID NO: 5; and atleast one framework region present in one of SEQ ID NOs: 48-63.
 45. Theisolated antibody or antigen-binding fragment of claim 44, wherein theantibody or antigen-binding fragment is selected from the groupconsisting of a single chain antibody, an scFv fragment, a Fab fragment,a F(ab′)₂ fragment, a humanized antibody, and a chimeric antibody. 46.The isolated antibody or antigen-binding fragment of claim 44, furthercomprising a human heavy chain constant region.
 47. The isolatedantibody or antigen-binding fragment of claim 46, wherein the humanheavy chain constant region comprises the amino acid sequence shown inone of SEQ ID NOs: 30 or
 31. 48. An isolated antibody that specificallybinds ILT3, or an antigen-binding fragment of the antibody, comprising:a heavy chain variable region (VH) complementarity determining region 1(VH CDR1) comprising the amino acid sequence shown in SEQ ID NO: 3; aheavy chain variable region (VH) complementarity determining region 2(VH CDR2) comprising the amino acid sequence shown in SEQ ID NO: 4; anda heavy chain variable region (VH) complementarity determining region 3(VH CDR3) comprising the amino acid sequence shown in SEQ ID NO: 5;wherein framework regions of the VH are human VH framework regions,except that one or more human framework amino acid residues of the humanVH framework regions are backmutated to corresponding murine amino acidresidues present in SEQ ID NO: 1; wherein the one or more humanframework amino acid residues backmutated to the corresponding murineamino acid residues are selected from the group consisting of: aminoacid residue number 3, 10, 19, 40, 42, 44, 49, 76, 78, 84, 88, 93, and97 of SEQ ID NO:
 29. 49. An isolated antibody that specifically bindsILT3, or an antigen-binding fragment of the antibody, comprising: alight chain variable region (VL) complementarity determining region 1(VL CDR1) comprising the amino acid sequence shown in SEQ ID NO: 6; alight chain variable region (VL) complementarity determining region 2(VL CDR2) comprising the amino acid sequence shown in SEQ ID NO: 7; alight chain variable region (VL) complementarity determining region 3(VL CDR3) comprising the amino acid sequence shown in SEQ ID NO: 8; andat least one framework region present in one of SEQ ID NOs: 36-47 or 64.50. The isolated antibody or antigen-binding fragment of claim 49,wherein the antibody or antigen-binding fragment is selected from thegroup consisting of a single chain antibody, an scFv fragment, a Fabfragment, a F(ab′)₂ fragment, a humanized antibody, and a chimericantibody.
 51. The isolated antibody or antigen-binding fragment of claim49, further comprising a human light chain constant region.
 52. Theisolated antibody or antigen-binding fragment of claim 51, wherein thehuman light chain constant region comprises the amino acid sequenceshown in SEQ ID NO:
 32. 53. An isolated antibody that specifically bindsILT3, or an antigen-binding fragment of the antibody, comprising: alight chain variable region (VL) complementarity determining region 1(VL CDR1) comprising the amino acid sequence shown in SEQ ID NO: 6; alight chain variable region (VL) complementarity determining region 2(VL CDR2) comprising the amino acid sequence shown in SEQ ID NO: 7; anda light chain variable region (VL) complementarity determining region 3(VL CDR3) comprising the amino acid sequence shown in SEQ ID NO: 8,wherein framework regions of the VL are human VL framework regions,except that one or more human framework amino acid residues of the humanVL framework regions are backmutated to corresponding murine amino acidresidues present in SEQ ID NO: 2; wherein the one or more humanframework amino acid residues backmutated to the corresponding murineamino acid residues are selected from the group consisting of: aminoacid residue number 3, 4, 9, 10, 13, 14, 15, 18, 20, 21, 22, 41, 42, 43,45, 46, 49, 58, 70, 76, 78, 79, 80, 84, 85, 86, 87, and 100 of SEQ IDNO:
 28. 54. An isolated antibody that specifically binds ILT3, or anantigen-binding fragment of the antibody, comprising: a heavy chainvariable region (VH) complementarity determining region 1 (VH CDR1)comprising the amino acid sequence shown in SEQ ID NO: 3; a heavy chainvariable region (VH) complementarity determining region 2 (VH CDR2)comprising the amino acid sequence shown in SEQ ID NO: 4; a heavy chainvariable region (VH) complementarity determining region 3 (VH CDR3)comprising the amino acid sequence shown in SEQ ID NO: 5; a light chainvariable region (VL) complementarity determining region 1 (VL CDR1)comprising the amino acid sequence shown in SEQ ID NO: 6; a light chainvariable region (VL) complementarity determining region 2 (VL CDR2)comprising the amino acid sequence shown in SEQ ID NO: 7; a light chainvariable region (VL) complementarity determining region 3 (VL CDR3)comprising the amino acid sequence shown in SEQ ID NO: 8; and at leastone framework region present in one of SEQ ID NOs: 36-64.
 55. Theisolated antibody or antigen-binding fragment of claim 54, wherein theantibody or antigen-binding fragment is selected from the groupconsisting of a single chain antibody, an scFv fragment, a Fab fragment,a F(ab′)₂ fragment, a humanized antibody, and a chimeric antibody. 56.The isolated antibody or antigen-binding fragment of claim 54, furthercomprising a human heavy chain constant region.
 57. The isolatedantibody or antigen-binding fragment of claim 56, wherein the humanheavy chain constant region comprises the amino acid sequence shown inone of SEQ ID NOs: 30-31.
 58. The isolated antibody or antigen-bindingfragment of claim 54, further comprising a human light chain constantregion.
 59. The isolated antibody or antigen-binding fragment of claim58, wherein the human light chain constant region comprises the aminoacid sequence shown in SEQ ID NO:
 32. 60. An isolated antibody thatspecifically binds ILT3, or an antigen-binding fragment of the antibody,comprising: a heavy chain variable region (VH) complementaritydetermining region 1 (VH CDR1) comprising the amino acid sequence shownin SEQ ID NO: 3; a heavy chain variable region (VH) complementaritydetermining region 2 (VH CDR2) comprising the amino acid sequence shownin SEQ ID NO: 4; a heavy chain variable region (VH) complementaritydetermining region 3 (VH CDR3) comprising the amino acid sequence shownin SEQ ID NO: 5; a light chain variable region (VL) complementaritydetermining region 1 (VL CDR1) comprising the amino acid sequence shownin SEQ ID NO: 6; a light chain variable region (VL) complementaritydetermining region 2 (VL CDR2) comprising the amino acid sequence shownin SEQ ID NO: 7; and a light chain variable region (VL) complementaritydetermining region 3 (VL CDR3) comprising the amino acid sequence shownin SEQ ID NO: 8; wherein framework regions of the VH and VL are human VHand VL framework regions, except that one or more human framework aminoacid residues of the human VH framework regions are backmutated tocorresponding murine amino acid residues present in SEQ ID NO: 1;wherein the one or more human framework amino acid residues backmutatedto the corresponding murine amino acid residues are selected from thegroup consisting of: amino acid residue number 3, 10, 19, 40, 42, 44,49, 76, 78, 84, 88, 93, and 97 of SEQ ID NO:
 29. 61. An isolatedantibody that specifically binds ILT3, or an antigen-binding fragment ofthe antibody, comprising: a heavy chain variable region (VH)complementarity determining region 1 (VH CDR1) comprising the amino acidsequence shown in SEQ ID NO: 3; a heavy chain variable region (VH)complementarity determining region 2 (VH CDR2) comprising the amino acidsequence shown in SEQ ID NO: 4; a heavy chain variable region (VH)complementarity determining region 3 (VH CDR3) comprising the amino acidsequence shown in SEQ ID NO: 5; a light chain variable region (VL)complementarity determining region 1 (VL CDR1) comprising the amino acidsequence shown in SEQ ID NO: 6; a light chain variable region (VL)complementarity determining region 2 (VL CDR2) comprising the amino acidsequence shown in SEQ ID NO: 7; and a light chain variable region (VL)complementarity determining region 3 (VL CDR3) comprising the amino acidsequence shown in SEQ ID NO: 8; wherein framework regions of the VH andVL are human VH and VL framework regions, except that one or more humanframework amino acid residues of the human VL framework regions arebackmutated to corresponding murine amino acid residues present in SEQID NO: 2; wherein the one or more human framework amino acid residuesbackmutated to the corresponding murine amino acid residues are selectedfrom the group consisting of: amino acid residue number 3, 4, 9, 10, 13,14, 15, 18, 20, 21, 22, 41, 42, 43, 45, 46, 49, 58, 70, 76, 78, 79, 80,84, 85, 86, 87, and 100 of SEQ ID NO:
 28. 62. An isolated antibody thatspecifically binds ILT3, or an antigen-binding fragment of the antibody,wherein the antibody or antigen-binding fragment competes for binding toILT3 with the antibody or antigen-binding fragment of claim
 44. 63. Anisolated antibody that specifically binds ILT3, or an antigen-bindingfragment of the antibody, wherein the antibody or antigen-bindingfragment competes for binding to ILT3 with the antibody orantigen-binding fragment of claim 49.